[5pt] Introduced a new `datetime` module for timestamp and interval support

[TarantoolBot]

Epic: Datetime remaining issues

Product: Tarantool
Since: 2.10.0
Root document:

• https://www.tarantool.io/en/doc/latest/reference/reference_lua/
• https://www.tarantool.io/en/doc/latest/book/box/data_model/#indexed-field-types -- to do in [3pt] Storage support for datetime values #2509 ?
• https://www.tarantool.io/en/doc/latest/book/box/data_model/#field-type-details -- to do in [3pt] Storage support for datetime values #2509 ?

SME: @ tsafin, @ igormunkin

Details

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.
Requested by @tsafin in tarantool/tarantool@43e10ed

UPD: See the latest info on implementation in https://github.com/tarantool/tarantool/wiki/Datetime-Internals