Pipewire server uses the global "settings" metadata for adjusting its own log level.
Make it a convention that clients may watch "log.level" in this metadata with their client id as subject, for setting their own log level dynamically.
Watch the global "settings" metadata for "log.level" changes for our id. On changes, set our log level accordingly.
wpctl: add set-log-level command
Add command for changing log level for Pipewire or Wireplumber daemons at runtime.
It can be done with pw-metadata, but make it easier so that the user doesn't need to look up Wireplumber client ids.
In principle the setting could also be in
sm-settings metadata, not sure that's really better though.