feature: new lua api: whoami, peer_info

Example:

```console
tarantool> picolib.whoami()
---
- raft_id: 1
  cluster_id: demo
  instance_id: i1
...

tarantool> picolib.peer_info("i1")
---
- raft_id: 1
  instance_id: i1
  instance_uuid: 68d4a766-4144-3248-aeb4-e212356716e4
  replicaset_uuid: e0df68c5-e7f9-395f-86b3-30ad9e1b7b07
  replicaset_id: r1
  advertise_address: localhost:3301
  target_grade: Online
  current_grade: Online
...
```