Finally add tab customization. This implementation is a
bit ugly, but I had to futureproof it for playlists and I'm
planning to clean up a lot of the duplicate code across the app.
This addition notably allows a default tab to be set, which is
something that was widely requested in #12. This UI rework finally
allows it to be added.
Modify the minimal wdiget so that it can work on Android 11 and below.
Was not actually that hard, mostly changing layouts around all things
considered. This also splits up the default view and the main widget
views, which makes managing UI state much easier.
Add the first widget implementation, the minimal widget. This took a
good 2 days of hacking and frustration to get the first prototype
working. And even then, its currently scoped to android 12 until I'm
able to port them. The implementation is still quite rough, but should
become manageable over time. More widgets will come.