By default a user might not have privileges to access the _schema space,
that will cause an error during schema_needs_upgrade(), which calls
get_version(). Fix this by using C variable dd_version_id, which is
updated in the _schema.version replace trigger.

There's a special case for upgrade() during bootstrap() - triggers are
disabled during bootstrap, that's why dd_version_id is not being updated.
Handle this by passing _initial_version=1.7.5 to the upgrade function.

Part of #7149

NO_DOC=internal
NO_CHANGELOG=internal

The patch introduces C and Lua methods for extracting position
of tuple in index. Multikey and functional indexes are not supported.

Also this patch extends method index_create_iterator_after and adds
implementation of iterator_position for memtx tree. Options
after and fetch_pos are added to Lua select as well (both FFI and LuaC).
All the types of memtx tree indexes are supported (multikey, functional).

NO_CHANGELOG=see later commits
NO_DOC=see later commits

Closes #7633
Closes #7636

Before this change there was no way to create a fiber that accepts
parameters without yielding from the current fiber using the c api. You
could pass the function arguments when calling fiber_start, but that
forces you to yield, which is not acceptable in some scenarios (e.g.
within a transaction).

This commit introduces 2 new functions to the api: fiber_set_ctx for
setting an pointer to a context of the given fiber and fiber_get_ctx for
accessing that context.

Closes https://github.com/tarantool/tarantool/issues/7669

@TarantoolBot document
Title: fiber: add fiber_set_ctx & fiber_get_ctx functions

Add 2 api functions: `fiber_set_ctx` & `fiber_get_ctx` which can be used
for passing data to a fiber. Previously this could be done via the
`fiber_start` function, except that this would force the current fiber
to yield, which is not acceptable in some scenarios (e.g. during a
transaction). Now you can create a fiber with `fiber_new`, set it's
contents with `fiber_set_ctx`, make it ready for execution with
`fiber_wakeup` and keep executing the current fiber.

strerror() is MT-Unsafe, because it uses a static buffer under the hood.
We should use strerror_r() instead, which takes a user-provided buffer.
The problem is there are two implementations of strerror_r(): XSI and
GNU. The first one returns an error code and always writes the message
to the beginning of the buffer while the second one returns a pointer to
a location within the buffer where the message starts. Let's introduce a
macro HAVE_STRERROR_R_GNU set if the GNU version is available and define
tt_strerror() which writes the message to the static buffer, like
tt_cstr() or tt_sprintf().

Note, we have to export tt_strerror(), because it is used by Lua via
FFI. We also need to make it available in the module API header, because
the say_syserror() macro uses strerror() directly. In order to avoid
adding tt_strerror() to the module API, we introduce an internal helper
function _say_strerror(), which calls tt_strerror().

NO_DOC=bug fix
NO_TEST=code is covered by existing tests

This commit introduces a new parse rule for compiling an unresolved
single expression. This simplifies the current implementation of
sql_expr_compile() and is useful for generating SQL expressions that can
be used in the core check constraint. This rule is for internal use
only.

Part of #6986

NO_DOC=will be added later
NO_TEST=refactoring
NO_CHANGELOG=will be added later

The Rust module (see the issue) needs a getter and a setter for decimal
values on the Lua stack. Let's make them part of the module API.

Part of #7228

@TarantoolBot document
Title: Lua/C functions for decimals in the module API

The following functions are added into the module API:

```c
/**
 * Allocate a new decimal on the Lua stack and return
 * a pointer to it.
 */
API_EXPORT box_decimal_t *
luaT_newdecimal(struct lua_State *L);

/**
 * Allocate a new decimal on the Lua stack with copy of given
 * decimal and return a pointer to it.
 */
API_EXPORT box_decimal_t *
luaT_pushdecimal(struct lua_State *L, const box_decimal_t *dec);

/**
 * Check whether a value on the Lua stack is a decimal.
 *
 * Returns a pointer to the decimal on a successful check,
 * NULL otherwise.
 */
API_EXPORT box_decimal_t *
luaT_isdecimal(struct lua_State *L, int index);
```

The main decision made in this patch is how large the public
`box_decimal_t` type should be. Let's look on some calculations.

We're interested in the following values.

* How much decimal digits is stored?
* Size of an internal decimal type (`sizeof(decimal_t)`).
* Size of a buffer to store a string representation of any valid
  `decimat_t` value.
* Largest signed integer type fully represented in decimal_t (number of
  bits).
* Largest unsigned integer type fully represented in decimal_t (number
  of bits).

Now `decimal_t` is defined to store 38 decimal digits. It means the
following values:

| digits | sizeof | string | int???_t | uint???_t |
| ------ | ------ | ------ | -------- | --------- |
| 38     | 36     | 52     | 126      | 127       |

In fact, decNumber (the library we currently use under the hood) allows
to vary the 'decimal digits per unit' parameter, which is 3 by default,
so we can choose density of the representation. For example, for given
38 digits the sizeof is 36 by default, but it may vary from 28 to 47
bytes:

| digits | sizeof     | string | int???_t | uint???_t |
| ------ | ---------- | ------ | -------- | --------- |
| 38     | 36 (28-47) | 52     | 126      | 127       |

If we'll want to store `int128_t` and `uint128_t` ranges, we'll need 39
digits:

| digits | sizeof     | string | int???_t | uint???_t |
| ------ | ---------- | ------ | -------- | --------- |
| 39     | 36 (29-48) | 53     | 130      | 129       |

If we'll want to store `int256_t` and `uint256_t` ranges:

| digits | sizeof     | string | int???_t | uint???_t |
| ------ | ---------- | ------ | -------- | --------- |
| 78     | 62 (48-87) | 92     | 260      | 259       |

If we'll want to store `int512_t` and `uint512_t` ranges:

| digits | sizeof       | string | int???_t | uint???_t |
| ------ | ------------ | ------ | -------- | --------- |
| 155    | 114 (84-164) | 169    | 515      | 514       |

The decision here is what we consdider as possible and what as unlikely.
The patch freeze the maximum amount of bytes in `decimal_t` as 64. So
we'll able to store 256 bit integers and will NOT able to store 512 bit
integers in a future (without the ABI breakage at least).

The script, which helps to calculate those tables, is at end of the
commit message.

Next, how else `box_decimal_*()` library is different from the internal
`decimal_*()`?

* Added a structure that may hold any decimal value from any current or
  future tarantool version.
* Added `box_decimal_copy()`.
* Left `strtodec()` out of scope -- we can add it later.
* Left `decimal_str()` out of scope -- it looks dangerous without at
  least a good explanation when data in the static buffer are
  invalidated. There is `box_decimal_to_string()` that writes to an
  explicitly provided buffer.
* Added `box_decimal_mp_*()` for encoding to/decoding from msgpack.
  Unlike `mp_decimal.h` functions, here we always have `box_decimal_t`
  as the first parameter.
* Left `decimal_pack()` out of scope, because a user unlikely wants to
  serialize a decimal value piece-by-piece.
* Exposed `decimal_unpack()` as `box_decimal_mp_decode_data()` to keep a
  consistent terminogoly around msgpack encoding/decoding.
* More detailed API description, grouping by functionality.

The script, which helps to calculate sizes around `decimal_t`:

```lua
-- See notes in decNumber.h.

-- DECOPUN: DECimal Digits Per UNit
local function unit_size(DECOPUN)
    assert(DECOPUN > 0 and DECOPUN < 10)
    if DECOPUN <= 2 then
        return 1
    elseif DECOPUN <= 4 then
        return 2
    end
    return 4
end

function sizeof_decimal_t(digits, DECOPUN)
    -- int32_t digits;
    -- int32_t exponent;
    -- uint8_t bits;
    -- <..padding..>
    -- <..units..>
    local us = unit_size(DECOPUN)
    local padding = us - 1
    local unit_count = math.ceil(digits / DECOPUN)
    return 4 + 4 + 1 + padding + us * unit_count
end

function string_buffer(digits)
    -- -9.{9...}E+999999999# (# is '\0')
    -- ^ ^      ^^^^^^^^^^^^
    return digits + 14
end

function binary_signed(digits)
    local x = 1
    while math.log10(2 ^ (x - 1)) < digits do
        x = x + 1
    end
    return x - 1
end

function binary_unsigned(digits)
    local x = 1
    while math.log10(2 ^ x) < digits do
        x = x + 1
    end
    return x - 1
end

function digits_for_binary_signed(x)
    return math.ceil(math.log10(2 ^ (x - 1)))
end

function digits_for_binary_unsigned(x)
    return math.ceil(math.log10(2 ^ x))
end

function summary(digits)
    print('digits', digits)
    local sizeof_min = math.huge
    local sizeof_max = 0
    local DECOPUN_sizeof_min
    local DECOPUN_sizeof_max
    for DECOPUN = 1, 9 do
        local sizeof = sizeof_decimal_t(digits, DECOPUN)
        print('sizeof', sizeof, 'DECOPUN', DECOPUN)
        if sizeof < sizeof_min then
            sizeof_min = sizeof
            DECOPUN_sizeof_min = DECOPUN
        end
        if sizeof > sizeof_max then
            sizeof_max = sizeof
            DECOPUN_sizeof_max = DECOPUN
        end
    end
    print('sizeof min', sizeof_min, 'DECOPUN', DECOPUN_sizeof_min)
    print('sizeof max', sizeof_max, 'DECOPUN', DECOPUN_sizeof_max)
    print('string', string_buffer(digits))
    print('int???_t', binary_signed(digits))
    print('uint???_t', binary_unsigned(digits))
end
```

Part of #7228

@TarantoolBot document
Title: Module API for decimals

See the declarations in `src/box/decimal.h` in tarantool sources.

The Rust module [1] leans on several internal symbols. They were open in
Tarantool 2.8 (see #2971 and #5932), but never were in the public API.
Tarantool 2.10.0 hides the symbols and we need a way to get them back to
use in the module.

We have the following options:

1. Design and expose a module API for fiber channels.
2. Export the symbols with a prefix like `tnt_internal_` (to don't spoil
   the global namespace).
3. Provide a `dlsym()` alike function to get an address of an internal
   symbol for users who knows what they're doing.

I think that the third way offers the best compromise between amount of
effort, quality of the result and opportunities to extend. In this
commit I hardcoded the list of functions to make the change as safe as
possible. Later I'll return here to autogenerate the list.

Exported the following function from the tarantool executable:

```c
void *
tnt_internal_symbol(const char *name);
```

I don't add it into the module API headers, because the function is to
perform a dark magic and we don't suggest it for users.

While I'm here, added `static` to a couple of fiber channel functions,
which are only used within the compilation unit.

[1]: https://github.com/picodata/tarantool-module

Part of #7228
Related to #6372

NO_DOC=don't advertize the dangerous API
NO_CHANGELOG=don't advertize the dangerous API

Added a function (see the API in the documentation request below), which
reflects the `tuple[json_path]` Lua API (see #1285).

Part of #7228

@TarantoolBot document
Title: tuple: access a field using JSON path via module API

The following function is added into the module API:

```c
/**
 * Return a raw tuple field in the MsgPack format pointed by
 * a JSON path.
 *
 * The JSON path includes the outmost field. For example, "c" in
 * ["a", ["b", "c"], "d"] can be accessed using "[2][2]" path (if
 * index_base is 1, as in Lua). If index_base is set to 0, the
 * same field will be pointed by the "[1][1]" path.
 *
 * The first JSON path token may be a field name if the tuple
 * has associated format with named fields. A field of a nested
 * map can be accessed in the same way: "foo.bar" or ".foo.bar".
 *
 * The return value is valid until the tuple is destroyed, see
 * box_tuple_ref().
 *
 * Return NULL if the field does not exist or if the JSON path is
 * malformed or invalid. Multikey JSON path token [*] is treated
 * as invalid in this context.
 *
 * \param tuple a tuple
 * \param path a JSON path
 * \param path_len a length of @a path
 * \param index_base 0 if array element indexes in @a path are
 *        zero-based (like in C) or 1 if they're one-based (like
 *        in Lua)
 * \retval a pointer to a field data if the field exists or NULL
 */
API_EXPORT const char *
box_tuple_field_by_path(box_tuple_t *tuple, const char *path,
			uint32_t path_len, int index_base);
```

The packpack-dont-decline-custom-version.patch file was introduced in
9707a7bd (github-ci: support the new version format) and tried to resolve
the issue that actually did not exist. PackPack supports accepting a
custom version (pay attention to `?=`) [1] and the patch is not needed.

[1] https://github.com/packpack/packpack/blob/194f898750cbbee6dd35255fe8aa7ec878eb3836/pack/config.mk#L45

NO_DOC=ci
NO_TEST=ci
NO_CHANGELOG=ci

This macro does nothing, so it is dropped.

NO_DOC=refactoring
NO_TEST=refactoring
NO_CHANGELOG=refactoring

By a mistake it was marked as API_EXPORT but was forgotten to
be added to exports.

Closes #7125

NO_DOC=bugfix

Properly calculate `isdst` field in datetime Lua object and
for attribute returned by `:totable()` function.

NO_DOC=next commit

LuaJIT submodule is bumped to introduce the following changes:
* sysprof: change C configuration API
* sysprof: enrich symtab on a new trace or a proto
* sysprof: fix SYSPROF_HANDLER_STACK_DEPTH
* sysprof: make internal API functions static
* sysprof: add LUAJIT_DISABLE_SYSPROF to Makefile
* symtab: check the _GNU_SOURCE definition

Within this changeset Tarantool-specific backtrace handler is introduced
and set to be used by sysprof machinery.

Besides, all new public Lua C API introduced within this changeset is
added to extra/exports.

Follows up #781

NO_DOC=LuaJIT submodule bump
NO_TEST=LuaJIT submodule bump
NO_CHANGELOG=LuaJIT submodule bump

This patch introduces operator [] that allows to get elements from MAP
and ARRAY values.

Closes #4762
Closes #4763
Part of #6251

@TarantoolBot document
Title: Operator [] in SQL

Operator `[]` allows to get an element of MAP and ARRAY values.
Examples:
```
tarantool> box.execute([[SELECT [1, 2, 3, 4, 5][3];]])
---
- metadata:
  - name: COLUMN_1
    type: any
  rows:
  - [3]
...

tarantool> box.execute([[SELECT {'a' : 123, 7: 'asd'}['a'];]])
---
- metadata:
  - name: COLUMN_1
    type: any
  rows:
  - [123]
...
```

The returned values is of type ANY.

If the operator is applied to a value that is not a MAP or ARRAY or is
NULL, an error is thrown.

Example:
```
tarantool> box.execute([[SELECT 1[1];]])
---
- null
- Selecting is only possible from map and array values
...
```

However, if there are two or more operators next to each other, the
second or following operators do not throw an error, but instead
return NULL.

Example:
```
tarantool> box.execute([[select [1][1][2][3][4];]])
---
- metadata:
  - name: COLUMN_1
    type: any
  rows:
  - [null]
...
```

Since recently we partially support timezone names (i.e. as
abbreviations) so we may modify tz attribute support for
datetime constructors or :set() operations.

Closes #7076
Relates to #7007

@TarantoolBot document
Title: datetime tz attribute

Now `tz` attribute is properly handled in datetime value
constructors or `:set{}` method modifiers.

```
tarantool> T = date.new{year = 1980, tz = 'MSK'}
---
...

tarantool> T.tzoffset
---
- 180
...

tarantool> T.tz
---
- MSK
...
tarantool> T = date.new{year = 1980, tzoffset = 180}
---
...

tarantool> T.tzindex
---
- 0
...

tarantool> T.tz
---
-
...

tarantool> T.tzoffset
---
- 180
...

tarantool> T:set{tz = 'MSK'}
---
...

tarantool> T.tz
---
- MSK
...

```

Box read operations (select, min, max, random, pairs) may call a Lua
function via Lua C API if space upgrade (EE feature) is in progress.
This is forbidden if the original function was called via FFI:

https://github.com/tarantool/luajit/commit/4f4fd9ebeb10d53c8e67f45170938f052818e64e

Let's add helper functions to disable FFI for box read operations.
We will use them in EE code.

NO_DOC=internal
NO_TEST=internal
NO_CHANGELOG=internal

Fix the following error:

    {"badRequest": {"message": "The requested availability zone is not
    available", "code": 400}}

NO_DOC=testing stuff
NO_TEST=testing stuff
NO_CHANGELOG=testing stuff

LuaJIT submodule is bumped to introduce the following changes:
* GC64: disable sysprof support
* build: make -DLUAJIT_DISABLE_SYSPROF work
* test: disable sysprof C API tests with backtrace
* tools: introduce parsers for sysprof
* sysprof: introduce Lua API
* memprof: add profile common section
* core: introduce lua and platform profiler
* memprof: move symtab to a separate module
* core: separate the profiling timer from lj_profile
* vm: save topframe info into global_State

Within this changeset a parser for binary data dumped via the sampling
profiler to Tarantool binary. It is a set of the following Lua modules:
* sysprof/parse.lua: decode the sampling profiler event stream
* sysprof/collapse.lua: collapse stacks obtained while profiling
* sysprof.lua: Lua script and module to display data

Besides, all new public Lua C API introduced within this changeset is
added to extra/exports.

Closes #781

NO_DOC=LuaJIT submodule bump
NO_TEST=LuaJIT submodule bump

This patch introduces basic INTERVAL support in SQL. After this patch,
it will be allowed to select INTERVAL values from spaces, insert them
into spaces, and use them in functions. CAST() from INTERVAL to STRING
and ANY is also supported.

Part of #6773

NO_DOC=Will be added later.
NO_CHANGELOG=Will be added later.

Part of #6773

NO_DOC=INTERVAL has already been introduced earlier.
NO_CHANGELOG=It will be added in another commit.

Split single sec field in the datetime_interval into multiple subfields,
i.e. week, day, hour, min, sec. Make sure that whatever we enter in the
constructor we get similarly visualized as textual representation

Lua implementation of datetime_totable has been converted to C, which
allows to use it for datetime values decomposing in datetimes
subtraction. It uses per component subtraction for calculating of a
resultant interval.

Part of #6923

NO_DOC=refactoring
NO_CHANGELOG=refactoring

Created C implementation for the rest of datetime/interval operations
and call them via FFI. We need it for later Olson integration.

Part of #6923

NO_DOC=refactoring
NO_CHANGELOG=refactoring
NO_TEST=refactoring, tests left intact

Convert Lua implementation of datetime_increment_by to C from their
Lua variant.

Part of #6923

NO_DOC=refactoring
NO_CHANGELOG=refactoring
NO_TEST=refactoring, tests left intact

Part of #6923

NO_DOC=refactoring
NO_CHANGELOG=refactoring
NO_TEST=refactoring, tests left intact

Simply add Lua wrappers for recently introduced prbuf.

Introduce new buffer (in addition to ibuf) - prbuf. "pr" stands for
"partitioned ring-". It save all metadata in the same memory chunk
provided for storage, so it can be completely restored from the 'raw'
memory. API:

```
-- mem is a chunk of raw (char *) memory, of size mem_size.
-- It is used for data storage. Note that available space is of less
-- size due to prbuf metadata overhead.
-- Returns handle to prbuf.
--
require('buffer').prbuf_create(mem, mem_size)

-- mem is a chunk of memory, which contains already created prbuf.
-- It implies that once prbuf_create() was called with the same memory.
-- If mem does not contain valid buffer - raise an appropriate error.
require('buffer').prbuf_open(mem)

-- Returns continuous chunk of memory with given size. May return nil
-- in case if requested chunk is too large. Note that after copying
-- object to returned chunk, it should be committed with prbuf:commit();
-- otherwise :prepare() may return the same chunk twice.
prbuf:prepare(size)

-- Commits the last prepared chunk. Undefined behaviour in case of
-- committing the same chunk twice.
prbuf:commit()

-- Create and return prbuf_iterator. Does not fail. Created iterator
-- points to nowhere - it should be adjusted with :next() call to
-- the first entry.
prbuf:iterator_create()

-- Advance iterator position. Returns prbuf_entry or nil in case
-- iterator has reached the end. Entry consists of two members:
-- size and ptr. The last one is an array of characters of given size.
iterator:next()
```

 Usage examples:

```

local ibuf = buffer.ibuf()
local prbuf_size = 100
local memory = ibuf:alloc(prbuf_size)
local prbuf = buffer.prbuf_create(memory, prbuf_size)

local sample_size = 4
local raw = prbuf:prepare(4)
if raw == nil then
    -- allocation size is too large, try smaller.
end
raw[0] = ...
...
raw[3] = ...
prbuf:commit()
local prbuf_recovered = buffer.prbuf_open(memory)
local iter = prbuf_recovered:iterator_create()
local entry = iter:next()
assert(tonumber(entry.size) == 4)
-- Check values stored in the buffer.
assert(entry.ptr[0] == ...)
entry = iter:next()
-- Our buffer has only one entry.
assert(entry == nil)

```

NO_DOC=<Feature for internal usage>
NO_CHANGELOG=<Feature for internal usage>

Currently `tarantoolctl rocks --help` generate such help message:

NAME
	/usr/bin/tarantoolctl - LuaRocks main command-line interface

SYNOPSIS
	/usr/bin/tarantoolctl [<flags...>] [VAR=VALUE]...

This is wrong.

This patch makes the output look like this:

NAME
	/usr/bin/tarantoolctl rocks - LuaRocks main command-line interface

SYNOPSIS
	/usr/bin/tarantoolctl rocks [<flags...>] [VAR=VALUE]...

NO_DOC=bugfix

An opportunity to call garbage collector of memtx transaction
manager manually allows to understand which garbage cannot be freed.
This knowledge can help us to improve garbage collector. Also this
opportunity makes it easier to test memtx mvcc memory monitoring.

Part of #6150

NO_DOC=internal feature
NO_CHANGELOG=internal feature
NO_TEST=internal feature

Now memtx TX manager tries to determine the best isolation level
by itself. There could be two options:
* READ_COMMITTED, when the transaction see changes of other tx
that are committed but not yet confirmed (written to WAL)
* READ_CONFIRMED, when the transaction see only confirmed changes.

Introduce a simple way to specify the isolation level explicitly:
box.begin{tx_isolation = 'default'} - the same as box.begin().
box.begin{tx_isolation = 'read-committed'} - READ_COMMITTED.
box.begin{tx_isolation = 'read-confirmed'} - READ_CONFIRMED.
box.begin{tx_isolation = 'best-effort'} - old automatic way.

Intrduce a bit more complex but potentially faster way to set
isolation level, like that:
my_level = box.tnx_isolation_level.READ_COMMITTED
..
box.begin{tx_isolation = my_level}

For simplicity of implementation also support symmetric values as
'READ_COMMITTED' and box.tnx_isolation_level['read-committed'].

Introduce a new box.cfg option - default_tx_isolation, that is
used as a default when a transaction is started. The option is
dynamic and possible values are the same as in box.begin, except
'default' which is meaningless.

In addition to string value the corresponding numeric values can
be used in both box.begin and box.cfg.

Part of #6930
NO_DOC=see later commits
NO_CHANGELOG=see later commits

* Default parse
  - new c-dt version used which handles extended years range
    while parse relaxed iso8601 gformat strings;
  - family of functions like dt_from_ymd_checked functions
    added to the new c-dt version, now used by conversion code
    to properly handle validation of a 32-bit boundary values;
  - datetime_parse_full() modified to properly handle huge years values;
  - added tests for extended years range.

* strptime-like parse
  - properly handle longer than 4 years values, negative values,
    and handle zulu suffix, which may be generated by Tarantool
    stringization routines;

Part of #6731

NO_DOC=internal
NO_CHANGELOG=internal

To parse date/time strings using format string we use
`strptime()` implementation from FreeBSD, which is
modified to use our `struct datetime` data structure.

List of supported format has been extended to include
`%f` which is flag used whenever you need to process
nanoseconds part of datetime value.

```
tarantool> T = date.parse('Thu Jan  1 03:00:00 1970', {format = '%c'})

tarantool> T
- 1970-01-01T03:00:00Z

tarantool> T = date.parse('12/31/2020', {format = '%m/%d/%y'})

tarantool> T
- 2020-12-31T00:00:00Z

tarantool> T = date.parse('1970-01-01T03:00:00.125000000+0300',
                          {format = '%FT%T.%f%z'})

tarantool> T
- 1970-01-01T03:00:00.125+0300
```

Part of #6731

NO_DOC=internal
NO_CHANGELOG=internal

Datetime module provides parse function to create
datetime object given input string.

`datetime.parse` function expect 1 required argument - which is
input string, and set of optional parameters passed as table
in 2nd argument.

Allowed attributes in this optional table are:
* `format` - should be either 'iso8601', 'rfc3339' or `strptime`-like
  format string. [strptime format will be added as part of next
  commit];
* `tzoffset` - to redefine offset of input string value, if there
  is no timezone provided.
* `tz` - human-readable, Olson database, timezone identifier, e.g.
  'Europe/Moscow'. Not yet implemented in this commit.

```
tarantool> T = date.parse('1970-01-01T00:00:00Z')

tarantool> T
- 1970-01-01T00:00:00Z

tarantool> T = date.parse('1970-01-01T00:00:00',
                          {format = 'iso8601', tzoffset = 180})

tarantool> T
- 1970-01-01T00:00:00+0300

tarantool> T = date.parse('2017-12-27T18:45:32.999999-05:00',
                          {format = 'rfc3339'})

tarantool> T
- 2017-12-27T18:45:32.999999-0500
```

Implemented as per RFC https://hackmd.io/@Mons/S1Vfc_axK#%D0%AD%D1%82%D0%B0%D0%BF-3-%D0%9F%D0%B0%D1%80%D1%81%D0%B8%D0%BD%D0%B3-%D0%B4%D0%B0%D1%82-%D0%BF%D0%BE-%D1%84%D0%BE%D1%80%D0%BC%D0%B0%D1%82%D1%83

Part of #6731

NO_DOC=internal
NO_CHANGELOG=internal

This patch introduces basic DATETIME support in SQL. After this patch,
it will be allowed to select DATETIME values from spaces, insert them
into spaces, and use them in functions. CAST() from DATETIME to STRING,
SCALAR and ANY is also supported.

Part of #6773

NO_DOC=Doc-request will be added in another commit.
NO_CHANGELOG=Changelog will be added in another commit.

Serialize `struct datetime` as newly introduced MP_EXT type.
It saves 1 required integer field and 3 optional fields:
- epoch is required field;
- but nsec, tzoffset and tzindex are optional;

* supported json, yaml serialization formats, lua output mode;

Please refer to the
https://hackmd.io/@Mons/S1Vfc_axK#%D0%A3%D0%BF%D0%B0%D0%BA%D0%BE%D0%B2%D0%BA%D0%B0-%D0%B2-msgpack
for a description of a messagepack serialization schema for datetime
values.

Follow-up to #5941
Part of #5946

Add interval arithmetics as date:add{} and date:sub{}, or
overloaded '+' and '-' operators (__add/_sub metamethods).
There is no special processing for timezone specific
daylight saving time changes, which impacts result of arithmetics.
This will be completed after Olsen database support added.

If one needs to control a way arithmetic proceeded for days
of months then there is optional argument to `:add()` or `:sub()`,
which defines how we round day in month after arithmetic
operation:

- 'last' - mode when day snaps to the end of month, if happens:

  -- 29.02.2004 -> 31.03.2004
  dt:add{month = 1, adjust = "last" }

- 'none' only truncation toward the end of month performed
  (**default mode**):

  -- 29.02.* -> 29.03.*
  dt:add{month = 1, adjust = "none" }

- 'excess' - overflow mode, without any snap or truncation to
  the end of month, straight addition of days in month, stopping
  over month boundaries if there is less number of days.

  dt = new{year = 2004, month = 1, day = 31}
  dt:add{month = 1, adjust = 'excess'} -> 02.03.2004

  -- i.e. there were 29 days in February 2004, 2 excessive days
     from original date 31 make result 2nd March 2004

Intervals objects, created via `datetime.interval.new()` call
and objects of the same attributes are equivalent for interval
arithmetics and exchangeable. i.e.

   dt + date.interval.new{year = 1, month = 2}

is the same as
   dt + {year = 1, month = 2}

Follow-up to #5941

Currently, we use the same luarocks hardcoded config for static build as
for regular build. As a result, LUA_BINDIR, LUA_INCDIR, SYSCONFDIR, and
PREFIX point to locations inside the build directory, which doesn't make
any sense.

Let's introduce a special hardcoded config which will set those
directories to locations relative to the binary location:

 - LUA_BINDIR: directory where the binary is located (bindir)
 - PREFIX: <dir> if bindir is <dir>/bin, otherwise bindir.
 - LUA_INCDIR: PREFIX/include/tarantool
 - SYSCONFDIR: PREFIX/etc/tarantool/rocks

Also, let's add the PREFIX/rocks to the rocks path if present.

This is needed for Tarantool SDK bundle to work as expected.
In particular the check for <dir>/bin is needed, because SDK
installs binaries in bundle root, not in /bin.

The options are not used anymore since update to 3.1.1,
see third_party/luarocks/src/luarocks/core/cfg.lua.

They should have been removed by commit
4222c1f6
("rocks: update luarocks to 3.1.1")

It contains Lua code. Format it appropriately. No functional changes.

Previously, URI can be passed as a string, which contains one URI
or several URIs separated by commas. Now URIs can be passed in
different ways: as before, as a table which contains URI and it's
parameters in "param" table, as a table which contains URI strings
and URI tables. Also there are different ways to specify properties
for URI: in a string which contains URI, after '?' delimiter, in a
table which contains URI in "params" table, in "default_params" table
if it is default parameters for all URIs.
For this purposes new method `parse_many` was implemented in tarantool
`uri` library. Also `parse` method was updated to make possible the
same as new `parse_many` method but only for single URI.
```lua
uri = require('uri')
-- Single URI, passed as before
uri.parse_many("/tmp/unix.sock")
-- Single URI, with query paramters
uri.parse_many("/tmp/unix.sock?q1=v1&q2=v2")
-- Several URIs with parameters in one string, separated by commas
uri.parse_many("/tmp/unix.sock_1?q=v, /tmp/unix.sock_2?q=v")
-- Single URI passed in table, with additional parameters, passed
-- in "params" table. This parameters overwrite parameters from
-- URI string (q1 = "v2" in example below).
uri.parse_many({"/tmp/unix.sock?q1=v1", params = {q1 = "v2"}})
-- For parse it's also works now
uri.parse({"/tmp/unix.sock?q1=v1", params = {q1 = "v2"}})
-- Several URIs passed in table with default parameters, passed
-- in "default_params" table, which are used for parameters, which
-- not specified for URI (q3 parameter with "v3" value corresponds
-- to all URIs, and used if there is no such parameter in URI).
uri.parse_many({
    "/tmp/unix.sock_1?q1=v1",
    { uri = "/tmp/unix.sock_2", params = { q2 = "v2" } },
    default_params = { q3 = "v3" }
})
```

Implement ability to parse a string, which contains several URIs
separated by commas. Each URI can contain different query parameters
after '?'. All created URIs saved in new implemented struct `uri_set`.

Part of #5928