debug-control: Allow to set and get log domains at runtime
Ever so often it would be interesting to get more details about the compositor state without restarting it. Let's make the log domains tweakable at runtime.
Example:
busctl --user set-property mobi.phosh.Phoc.DebugControl /mobi/phosh/Phoc/DebugControl mobi.phosh.Phoc.DebugControl LogDomains as 2 phoc-wlroots phoc-layer-surface