main: introduce new CLI options for config module

There are two new options introduced in Tarantool CLI:
* --name (-n) to specify instance name to be started. The option can be
  omitted in case TT_INSTANCE_NAME environment variable is set.
* --config (-c) to specify the path to the config file. If the option
  is not set the value of TT_CONFIG environment variable is considered.

Closes #8613

Co-authored-by: Sergey Bronnikov <sergeyb@tarantool.org>

@TarantoolBot document
Title: introduce new CLI options for conf module

There are two new options introduced in Tarantool CLI:
* --name (-n) to specify instance name to be started. The option can be
  omitted in case TT_INSTANCE_NAME environment variable is set.
* --config (-c) to specify the path to the config file. If the option
  is not set the value of TT_CONFIG environment variable is considered.