[Release-1.0] Preferred platform

[Yagich]

Issue: playlists with multiple people in can contain music items from different platforms like Spotify, YT Music and Apple Music. However, there is currently no way to "switch" between platforms, nor is it clear what the user's "preferred" platform is.

Proposal:

• [ ] When a user logs in with a platform, it is considered their preferred, therefore tracks added to playlists should be from that platform;
• [ ] Playlists should be able to contain music items from different platforms, and when a user selects a song that was added from a platform different from the user's preferred it should perform a search for this song and open it in the preferred platform.

Perhaps it would make sense to provide the ability to choose what platform to add songs from, to circumvent country/region blocks on certain platforms?

[adilanchian]

This will most likely be a setting in the profile page that we end up creating