0xc1 isn't a valid MsgPack header, but it was allowed by mp_check.
As a result, msgpack.decode crashed while trying to decode it.
This commit updates the msgpuck library to fix this issue.

Closes #7818

NO_DOC=bug fix

(cherry picked from commit ced405af)

NO_CHANGELOG=feature was not released

Closes #6823

@TarantoolBot document
Title: Document msgpack object iterator take_array method

The new method copies the given number of msgpack values starting from
the iterator cursor position to a new msgpack array object. On success
it returns the new msgpack object and advances the iterator cursor. If
there isn't enough values to decode, it raises a Lua error and leaves
the iterator cursor unchanged.

This function could be implemented in Lua like this:

```lua
function take_array(iter, count)
    local array = {}
    for _ = 1, count do
        table.insert(array, iter:take())
    end
    return msgpack.object(array)
end
```

Usage example:

```lua
local mp = msgpack.object({10, 20, 30, 40})
local it = mp:iterator()
it:decode_array_header()       -- returns 4
it:decode()                    -- returns 10
local mp2 = it:take_array(2)
mp2:decode()                   -- returns {20, 30}
it:decode()                    -- returns 40
```

Closes #1629
Closes #3909
Closes #5316
Needed for #3349
Needed for #4861

@TarantoolBot document
Title: Document msgpack.object

The following new methods were added to the Lua `msgpack` module:
 - `msgpack.object()`: Encodes an arbitrary Lua object given in its only
   argument in MsgPack and returns the encoded MsgPack data encapsulated
   in a MsgPack object.
 - `msgpack.object_from_raw()`: Creates a MsgPack object from raw data
   given either as a string or as a pointer and size.
 - `msgpack.is_object()`: Checks is the given argument is a MsgPack
   object.

Example:

```lua
local buffer = require('buffer')
local msgpack = require('msgpack')
-- Create an object from a Lua object.
local mp = msgpack.object(123)
local mp = msgpack.object("foobar")
local mp = msgpack.object({1, 2, 3})
local mp = msgpack.object({foo = 1, bar = 2})
local mp = msgpack.object(box.tuple.new(1, 2, 3))
-- Create an object from raw data given as a string.
local data = msgpack.encode({1, 2, 3})
local mp = msgpack.object_from_raw(data)
-- Create an object from raw data given as ptr and size.
local buf = buffer.ibuf()
msgpack.encode({1, 2, 3}, buf)
local mp = msgpack.object_from_raw(buf.buf, buf:size())
-- Check object.
msgpack.is_object(mp) -- true
msgpack.is_object({}) -- false
```

A MsgPack object has the following methods:

 - `mp:decode()`: Decodes MsgPack and returns a Lua object.
 - `mp:iterator()`: Returns an iterator over MsgPack data.

A MsgPack iterator has the following methods:

 - `it:decode_array_header()`: Decodes a MsgPack array header under the
   cursor and returns the number of elements in the array. After calling
   this function the iterator points to the first element of the array
   or to the value following the array if the array is empty. Raises an
   error if the type of the value under the iterator cursor is not
   `MP_ARRAY`.
 - `it:decode_map_header()`: Decodes a MsgPack map header under the
   cursor and returns the number of key value pairs in the map. After
   calling this function the iterator points to the first key stored in
   the map or to the value following the map if the map is empty. Raises
   an error if the type of the value under the iterator cursor is not
   `MP_MAP`.
 - `it:decode()`: Decodes a MsgPack value under the iterator cursor and
   advances the cursor. Returns a Lua object corresponding to the
   MsgPack value. Raises a Lua error if there's no data to decode.
 - `it:take()`: Returns a MsgPack value under the iterator cursor as a
   MsgPack object (without decoding). Raises a Lua error if there's no
   data to decode. This function doesn't copy MsgPack data - instead it
   takes a reference to the original object.
 - `it:skip()`: Advances the iterator cursor by skipping one MsgPack
   value under the cursor. Returns nothing. Raises a Lua error if
   there's not data to skip.

Usage example:

```lua
local msgpack = require('msgpack')
local mp = msgpack.object({foo = 123, bar = {1, 2, 3}})
local it = mp:iterator()
it:decode_map_header()  -- returns 2
it:decode()             -- returns 'foo'
it:decode()             -- returns 123
it:skip()               -- returns none, skips 'bar'
local mp2 = it:take()
mp2:decode()            -- returns {1, 2, 3}
```

For more examples, see `test/app-luatest/msgpack_test.lua`.

A MsgPack object can be passed to MsgPack encoder with the effect being
the same as passing the original Lua object:

```lua
local msgpack = require('msgpack')
local mp = msgpack.object(123)
msgpack.object({mp, mp}):decode()         -- returns {123, 123}
msgpack.decode(msgpack.encode({mp, mp}))  -- returns {123, 123}
```

In particular, this means that if a MsgPack object stores an array,
it can be inserted into a database space:

```lua
box.space.my_space:insert(msgpack.object({1, 2, 3}))
```

Use luatest for checking correctness behavioral for encode/decode
functions

Delete msgpack.test.lua.

Part of tarantool/test-run#304