feat(audit): implement composite record id

Logically, the record id consists of 3 fields:
* `raft_id` -- raft id of the current node (or `null` if uninitialized);
* `count` -- in-memory id which is auto incremented for each new record;
* `gen` -- persistent id which is incremented each time node is started.

However, in practice they are stored inside a global `LogicalClock`.

This is what the record looks like now:

```json
{
  "id": "1.0.3",
  "instance_id": "i1",
  "message": "a new instance `i1` joined the cluster",
  "raft_id": "1",
  "severity": "low",
  "time": "2023-11-29T17:07:36.524+0300",
  "title": "join_instance"
}
```

Note how those fields are concatenated using `.`; the resulting
unique id is represented by a json string type.

Furthermore, since audit record logger now depends on the
raft machine's state, we decided to move its initialization
further into the init sequence (postjoin).