[WIP] Spotify Implementation

[sakofchit]

Decided that each music service implementation should have its own separate issue to keep track of them better.

We're using this package btw: https://github.com/brim-borium/spotify_sdk

#14

[fritzlb]

With this package we’ll have to make its license visible to the user, too. Maybe just another menu like settings -> credits or something If I have enough free Mac storage I could do this today

[sakofchit]

yeah that would work 👍