Fingel/gelly

This is a substantial release with some long requested features and improvements under the hood.

I've written up my experience with one of the wildest server side bugs while working on this release. Give it a read if interested!

The long requested favorites feature is finally here. You can mark songs, albums, artists
and playlists as favorites and filter by them in the library. There is also a new "Favorites Mix"
smart playlist which combines all favorited songs, plus all songs from all favorited albums and
artists. There is also a new keyboard shortcut: ctrl+s to toggle filtering by favorite. Enjoy!

The blurred background art effect will now transition smoothy when changing songs. This was
difficult to figure out but it turned out well. Thank you G4Music for the code inspiration.

https://github.com/user-attachments/assets/0fb12fcb-0fde-4932-8555-c067fa1f655c

Gelly will now be more forgiving of missing metadata - specifically missing album information. A
win for the lazy.

The player bar has been re-arranged, again. The new "favorite" button was the straw that broke
the camel's back with the old design, the new one should feel less cluttered.

Updated to the GNOME 50 runtime.

List views have been refactored to do searching/sorting in a more idiomatic way. This should
improve performance for those with massive libraries and/or slower computers.

Full Changelog: https://github.com/Fingel/gelly/compare/v1.1.2...v1.2.0