Various small new-string-introducing improvements

Unify "songs" to read "tracks" in ui everywhere.

BUG: 343896

Introduce new, more descriptive strings in existing Wikipedia applet buttons. Add option to copy image to clipboard. Show a clickable link when trying to open a non-Wikipedia url.

Add "Never Played" preset to collection filter widget. Suggested by Robert Marshall - thank you!

Show name or count of playlists in deletion confirmation dialog

BUG: 234854