Use these new functions as well as new signals to simplify toggle state in playerbar, as well as ensure changes over MPRIS allow for the updating of our UX.
Implement method handlers and relevant setters for MPRIS support, as well as a koto_update_mpris_playback_state used to notify on state changes.
Clean up some debugging.
Implemented the following getters for MPRIS:
- CanQuit
- CanRaise
- HasTrackList
- Identity
- DesktopEntry
- SupportedUriSchemas
- SupportedMimeTypes
- Metadata
- CanPlay / CanPause / CanSeek
- CanControl
- PlaybackStatus
Implemented a koto_push_track_info_to_builder function that enables us to easily push KotoIndexedTrack as well as associated album and artist info to a GVariantBuilder for use in a GVariant for various getters.
Implemented a koto_update_mpris_info_for_track function that emits a signal for PropertiesChanged + "Metadata" when our track info changes.
