vshard: vshard.router.info shows name

[TarantoolBot]

Related dev. issue: tarantool/vshard#426
Related doc. issues: #3942, #3943

Product: Tarantool, vshard
Since: 3.0, 0.1.25
Root document: https://www.tarantool.io/en/doc/latest/reference/reference_rock/vshard/vshard_router/
SME: @ Totktonada, @ Serpentian

Details

When identification_mode is name_as_key, persisted master and
replicaset name is shown in vshard.router.info:

tarantool> vshard.router.info()
---
- replicasets:
    replicaset_1:
      replica: &0
        network_timeout: 0.5
        status: available
        uri: storage@127.0.0.1:3303
        name: replica_1_a
      name: replicaset_1
      master: *0

Requested by @Serpentian in tarantool/vshard@4c14eb4.