feat: enable configuration hot-reloading

[ManuelBilbao]

Added hot-reloading for configuration in PBS and signer modules. This expose a /reload endpoint on each module that re-parse the configuration file and apply the changes to their config/manager structures.
Changes to listening hosts and ports will not be applied as they require the server to restart. Also, path-related changes may not work if the module is running in Docker, as they require the container to be recreated.

Close #219

[ltitanb]

mm let's check with @blevkivskyi-everstake what would be his preferred use case but this feels a bit overly complicated to me? why not just have a watcher to the file (eg with notify) and trigger a config update when it's modified?

[blevkivskyi-everstake]

I'm not sure if it will work correctly with container environments.
Also, there is a corner case where the config is invalid, and commit-boost will crash on the next reload.

[ltitanb]

I would say that if the reload fails, then the config is not updated. At startup it would fail ofc which is the normal behaviour

[blevkivskyi-everstake]

If it works with files from includes - ok

[ManuelBilbao]

why not just have a watcher to the file (eg with notify) and trigger a config update when it's modified?

I thought that instant updates can cause some problems, as you might save the file several times before having a desirable version? Having an endpoint instead gives you control over when the config is updated.
Let me know if you consider that this is not a problem and I'll take that approach

I would say that if the reload fails, then the config is not updated. At startup it would fail ofc which is the normal behaviour

That is correct. If the reload fails (i.e. some config is wrong), the config is not updated and the request returns a 500 error.

If it works with files from includes - ok

Just to clarify, do you want to hot-reload the server when pubkey_commit_boost/test_mux.json change in addition to the config file?

[blevkivskyi-everstake]

Just to clarify, do you want to hot-reload the server when pubkey_commit_boost/test_mux.json change in addition to the config file?

Yes.

[ManuelBilbao]

The current implementation should work then, using the /reload endpoint. Let me know if you prefer the file watcher option (automatic updates on save) instead.

[ank-everstake]

Yes, reloading all included files is required.
We prefer /reload option that gives more flexibility and control then the file watcher.

[ltitanb]

Looks great overall! Some smaller changes/suggestions