box: introduce on_recovery_state triggers

Introduce triggers which are run during various stages of box.cfg{}.
See the docbot request below for more info.

Part-of #5272
Part-of #3159

@TarantoolBot document
Title: new triggers -- `box.ctl.on_recovery_state`

`box.ctl.on_recovery_state` is a handle to register triggers that will
be executed on different stages of recovery/initial configuration.
A trigger registered this way is run on each of the supported recovery
stages, and receives the stage name as a parameter. The possible stages
are:
 - "snapshot_recovered": the node has recovered the snapshot file.
 - "wal_recovered": the node has recovered all the .xlog files.
 - "indexes_built": all the secondary indexes are usable. This event
   might come even before any actual data is recovered, meaning that the
   indexes will be available right with the first recovered tuple.
 - "synced": the node has synced with enough remote peers and has left
   orphan state.

All these stages are passed during initial `box.cfg` call when recovering
from .snap and .xlog files.

When bootstrapping a fresh cluster with no data, all the instances in it
will still execute triggers on the same stages for consistency.
For example, "snapshot_recovered" and "wal_recovered" will
be run once the node finishes cluster bootstrap or finishes joining to an
existing cluster.

Anyway, by the time the initial `box.cfg` call finishes, regardless of
recovery or bootstrap, the triggers will be called with parameters
"snapshot_recovery", "wal_recovered" and "indexes_built". The triggers
on "synced" state might execute later, when the node leaves the orphan
mode.

Note, that you must set `box.ctl.on_recovery_state` triggers before the
initial `box.cfg` call for them to take effect.
Example:

NO_WRAP
```
Tarantool 2.11.0
type 'help' for interactive help
tarantool> log = require('log')
---
...

tarantool> trigger_f = function(state) log.info('State "' .. state .. '" reached') end
---
...

tarantool> box.ctl.on_recovery_state(trigger_f)
---
- 'function: 0x0104662788'
...

tarantool> box.cfg{}
<stripped some messages>
2022-11-15 13:21:43.149 [98398] main/103/interactive I> recovering from `./00000000000000000004.snap'
2022-11-15 13:21:43.166 [98398] main/103/interactive I> cluster uuid 75c5c40e-c795-4c6f-b602-25fe5b1c9f3b
2022-11-15 13:21:43.187 [98398] main/103/interactive I> assigned id 1 to replica 1fbcb1d7-f600-4cc6-83b4-8d409d2937a9
2022-11-15 13:21:43.187 [98398] main/103/interactive I> update replication_synchro_quorum = 1
2022-11-15 13:21:43.187 [98398] main/103/interactive I> State "snapshot_recovered" reached
                                                               ^^^^^^^^^^^^^^^^^^
2022-11-15 13:21:43.187 [98398] main/103/interactive I> recover from `./00000000000000000004.xlog'
2022-11-15 13:21:43.188 [98398] main/103/interactive I> done `./00000000000000000004.xlog'
2022-11-15 13:21:43.188 [98398] main/103/interactive I> recover from `./00000000000000000006.xlog'
2022-11-15 13:21:43.188 [98398] main/103/interactive I> done `./00000000000000000006.xlog'
2022-11-15 13:21:43.188 [98398] main/103/interactive I> Building secondary indexes in space 'test'...
2022-11-15 13:21:43.188 [98398] main/103/interactive I> Adding 2 keys to TREE index 'sk' ...
2022-11-15 13:21:43.188 [98398] main/103/interactive I> Space 'test': done
2022-11-15 13:21:43.188 [98398] main/103/interactive I> State "indexes_built" reached
                                                               ^^^^^^^^^^^^^
2022-11-15 13:21:43.189 [98398] main/103/interactive I> State "wal_recovered" reached
                                                               ^^^^^^^^^^^^^
2022-11-15 13:21:43.189 [98398] main/103/interactive I> ready to accept requests
2022-11-15 13:21:43.189 [98398] main/103/interactive I> State "synced" reached
                                                               ^^^^^^
2022-11-15 13:21:43.189 [98398] main/103/interactive I> leaving orphan mode
<stripped some messages>
---
...

tarantool>

```
NO_WRAP