"star" songs and filter for "starred only"

[Mathis Dirksen-Thedens]

• It should be possible to mark indiviual songs as "starred" (and back).
• There should be a button/icon to switch the list view to "starred only" (and back).
• The user should be able to "un-star" all songs at once.

The purpose of this is to allow for creating a set list for a worship session. The musicians can use a tablet and mark the songs planned for the session, then switch to "starred only" and use the list to easily jump from song to song.