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

In the future, it is planned to extend the URI structure to allow its
passing with different options and in different formats (see next commit
`uri: implement ability to parse URI query paramters` for example). For
these purposes, it is planned to use functions that modify the source
string, for example `strtok_r`, so we need to rework the URI structure
to create copies of the string for each of the URI components.

Part of #5928

Without it `tarantoolctl rocks` would require luarocks to be installed
on the system, which isn't always possible.

Use of PROJECT_ prefix gives ability to build the project as a
submodule of other projects.

In FreeBSD sed is not support \s as whitespace characters definition.
However, since FreeBSD-13 sed behaivour changed from ignore to error:
sed complains about trailing backslash (\). We should use whitespace
definition from POSIX standart.

More info: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=253893



CLoses #6637

Signed-off-by: Pavel Balaev <balaev@tarantool.org>

This patch introduces MAP to SQL. After this patch, all SQL operations
and built-in functions should work correctly with MAP values. However,
there is currently no way to create MAP values using only SQL tools.

Part of #4763

@TarantoolBot document
Title: Field type MAP in SQL

Properties of type MAP in SQL:
1) a value of type MAP can be implicitly and explicitly cast only to
ANY;
2) only a value of type ANY with primitive type MAP can be explicitly
cast to MAP;
3) a value of any other type cannot be implicitly cast to MAP;
4) a value of type MAP cannot participate in arithmetic, bitwise,
comparison, and concatination operations.

This patch introduces ARRAY to SQL. After this patch, all SQL operations
and built-in functions should work correctly with ARRAY values. However,
there is currently no way to create ARRAY values using only SQL tools.

Part of #4762

@TarantoolBot document
Title: Field type ARRAY in SQL

Properties of type ARRAY in SQL:
1) a value of type ARRAY can be implicitly and explicitly cast only
   to ANY;
2) only a value of type ANY with primitive type ARRAY can be explicitly
   cast to ARRAY;
3) a value of any other type cannot be implicitly cast to ARRAY;
4) a value of type ARRAY cannot participate in arithmetic, bitwise,
   comparison, and concatination operations.

In Lua struct error used RTTI to return members of the error
depending on its type. If a field was added to error's payload, it
wasn't visible. The patch makes Lua use error_payload instead of
RTTI. Now if the payload gets a new field, it becomes
automatically visible in Lua without need to introduce a new
method for it.

Part of #5568
Part of #4610
Part of #4907

Closes #3174

@TarantoolBot document
Title: Field type ANY in SQL

Properties of type ANY in SQL:
1) typeof() with an argument of type ANY returns "any";
2) any value of any type can be implicitly and explicitly cast to the ANY type;
3) a value of type ANY cannot be implicitly cast to any other type;
4) a value of type ANY cannot participate in arithmetic, bitwise, comparison,
   and concationation operations.

Jepsen testing starts one or several virtual machines and runs tarantool
instances on them. The first (first important for us here) command on
the virtual machine is `apt-get <...> update`: we should download
packages list to allow Jepsen to install necessary dependencies.

However we can access the virtual machine (using ssh) before it is fully
initialized by the cloud-init script. In particular, the cloud-init
script replaces apt's mirror list file (`/etc/apt/sources.list`).

Normally we should call `apt-get <...> update` after the package list
update, but here cloud-init races with the update command.

In the bad case the commands are executed in the opposite order:

* Terraform calls `apt-get <...> update`.
* cloud-init replaces `/etc/apt/sources.list`.

Now an attempt to install a package using apt-get will give the 'unable
to locate package' error, because we have no packages list for the 'new'
mirrors.

The problem is nicely described in [1]. See also the linked issue for
details.

[1]: https://github.com/hashicorp/packer/issues/41#issuecomment-21288589

Fixes https://github.com/tarantool/jepsen.tarantool/issues/87

Client code errors or manual mistakes can create transactions that are
never closed. Such transaction will work as a memory leak. Implement
timeout for transactions after which they are rolled back.

Part of #6177

@TarantoolBot document
Title: ability to set timeout for transactions was implemented
Previously transactions are never closed until commit or rollback.
Timeout for transactions was implemented after which they are rolled
back. For these purpose, in `box.begin` the optional table parameter
was added. For example if user want to start transaction with timeout
3s, he should use `box.begin({timeout = 3})`. Also was implement new
configuration option `box.cfg.txn_timeout` which determines timeout for
transactions, for which the timeout was not explicitly set. By default
this option is set to infinity (TIMEOUT_INFINITY = 365 * 100 * 86400).
Also in C API was added new function to set timeout for transaction -
'box_txn_set_timeout'.

Introduce a new builtin Tarantool module `datetime.lua` for timestamp
and interval types support.

New third_party module - c-dt
-----------------------------

* Integrated chansen/c-dt parser as 3rd party module to the
  Tarantool cmake build process;
* We use tarantool/c-dt instead of original chansen/c-dt to
  have an easier cmake build integration, as we have added some
  changes, which provide cmake support, and allow to rename symbols
  if necessary (this symbol renaming is similar to that we see
  with xxhash or icu).

New built-in module `datetime`
------------------------------

* created a new Tarantool built-in module `datetime`, which uses
  `struct datetime` data structure for keeping timestamp values;
* Lua module uses a number of `dt_*` functions from `c-dt` library,
  but they were renamed to `tnt_dt_*` at the moment of exporting
  from executable - to avoid possible name clashes with external
  libraries.

* At the moment we libc `strftime` for formatting of datetime
  values according to flags passed, i.e. `date:format('%FT%T%z')`
  will return something like '1970-01-01T00:00:00+0000', but
  `date:format('%A %d, %B %Y')` will return 'Thursday 01, January 1970'

* if there is no format provided then we use default
  `tnt_datetime_to_string()` function, which converts datetime
  to their default ISO-8601 output format, i.e.
  `tostring(date)` will return string like "1970-01-01T00:00:00Z"

* There are a number of simplified interfaces
  - totable() for exporting table with attributes names as provided
    by `os.date('*t')`
  - set() method provides unified interface to set values using
    the set of attributes as defined above in totable()

Example,

```
local dt = datetime.new {
	nsec      = 123456789,

	sec       = 19,
	min       = 29,
	hour      = 18,

	day       = 20,
	month     = 8,
	year      = 2021,

	tzoffset  = 180
}

local t = dt:totable()
--[[
{
	sec = 19,
	min = 29,
	wday = 6,
	day = 20,
	nsec = 123456789,
	isdst = false,
	yday = 232,
	tzoffset = 180,
	month = 8,
	year = 2021,
	hour = 18
}
--]]

dt:format()   -- 2021-08-21T14:53:34.032Z
dt:format('%Y-%m-%dT%H:%M:%S')   -- 2021-08-21T14:53:34

dt:set {
	usec      = 123456,

	sec       = 19,
	min       = 29,
	hour      = 18,

	day       = 20,
	month     = 8,
	year      = 2021,

	tzoffset  = 180,

}
dt:set {
	timestamp = 1629476485.124,

	tzoffset  = 180,
}

```

Coverage is

File                 Hits Missed Coverage
-----------------------------------------
builtin/datetime.lua 299  23     92.86%
-----------------------------------------
Total                299  23     92.86%

Part of #5941

@TarantoolBot document
Title: Introduced a new `datetime` module for timestamp and interval support

Create `datetime` module for timestamp and interval types support.
It allows to create date and timestamp values using either object interface,
or via parsing of string values conforming to iso-8601 standard.
One may manipulate (modify, subtract or add) timestamp and interval values.

Please refer to https://hackmd.io/@Mons/S1Vfc_axK#Datetime-in-Tarantool
for a more detailed description of module API.