Add settings for finer control over debug log level.

[Nerivec]

Implements #22342 via regex-based string setting.

Add setting to publish debug level to MQTT (and frontend).
Transport created is slightly different, based on that setting on startup, to avoid unnecessary runtime checks.

TODO:

• Add debug log settings docs. zigbee2mqtt.io#2737

[Koenkk]

Introduce settings in other schemas.

What other schemas do you mean here?

[Nerivec]

I had this in mind, but they don't have that section of the configuration.yaml. So I guess none?

[Koenkk]

Hass addon doesn't have to be updated, it's is configured via the UI.

Note to self; after this merge Koenkk/zigbee2mqtt.io#2737