allow scrobbling without lastfm or listenbrainz

[sentriz]

I don't have a last.fm key set in gonic. I don't actually want to scrobble to last.fm, I just want to scrobble to gonic itself so I can use the "Recently Played" album list in clients. Other clients (Supersonic, Ultrasonic) do scrobble to gonic without the last.fm API key being set. Maybe because they are ignoring the scrobblingEnabled field?

Originally posted by @gardebreak in #538

we always return scrobblingEnabled true, we let the scrobble.view endpoint decide if it can scrobble to external services. but it always update local gonic stats