Change the parent artist navigation so that its only enabled when an album is selected from LibraryFragment, otherwise dont enable it, as the user can just navigate up to see the parent artist.
Update layouts to not assign a primary color through the tools namespace anymore, also bring back the light theme, which apparently disappeared at some point.
Remove MusicRepository/All Library models and replace it with a single shared ViewModel, Move MainFragment into MainActivity, and remove the LoadingFragment -> MainFragment navigation path.
Turns out a dedicated Now Playing screen wont look that good, so refactor that into the Library screen. Also replace the ActionBar with a Toolbar and update the theming a bit.
