Configured names in config:info() and box.info.config

[TarantoolBot]

An instance in the YAML configuration always has a name and always
corresponds to a particular replicaset and a particular group. This is
forced by the hierarchical configuration format.

These names are now reported in config:info() and box.info.config.

# tarantool> config:info()
# or
# tarantool> config:info('v2')
# or
# tarantool> box.info.config
---
- <..status, alerts, meta..>
  hierarchy:
    group: group-001
    replicaset: replicaset-001
    instance: instance-001
...

The hierarchy field is an empty table if tarantool is started with a
Lua script or in the interactive mode without a script/a config.

Usually box.info.name equals to box.info.config.hierarchy.instance,
but there are situations, when only one of them is reported.

box.info.config.hierarchy.instance corresponds to the configured
instance name and it is reported when the YAML configuration is in use.
This instance name is written to the database as well, but the write
operation is postponed if the database schema version is lower then
needed to support the persistent names (see 1 for details).

A user can meet this situation while running tarantool 3.x on data from
tarantool 2.x, before the upgrading procedure is performed.

On the other hand, a user may use the persistent names feature (see 2)
together with the classic approach, when tarantool is run without the
configuration file, using a Lua script. In this case,
box.info.config.hierarchy is empty, but box.info.name shows the name
passed to box.cfg({instance_name = <...>}) (and written to the
database).

The same is applicable to box.info.replicaset.name and
box.info.config.hierarchy.replicaset.

Requested by @Totktonada in tarantool/tarantool@caf08d4.