[All Platforms][Playlists] Button to add a song to a default playlist

Add a super-reachable fast button (like the like button) to add the song to the users default playlist.


Which playlist is the default playlist in the sense of this button should of course be configurebale.


This has been bothering me for a while now. It's too cumbersome to add tracks to a playlist, should have a one click option both next to the track (like on a playlist radio) and on the screen controls.