[Feature Request] User favorites

[Mark-H]

Add the ability for users to save specific songs in specific streamers' songlists as their personal favorites. This would only be available in the app for users that are logged in, but also available in chat for follower+.

In the app, users should be able to mark a song as a favorite from both the queue and the songlist with a heart or star icon. There would also be a new page that lists their favorited songs in the songlist.

In chat, users could type !favesong (admin customisable) to easily save the current song (num 1 in queue) to their favorites, if they're hearing a tune they really like.

Perhaps chat also needs a !faves command to list their favorite songs, but that could also link to the favorites page in the songlist to avoid too much chat spam.

Future enhancements could include requesting a song from your favorites (!srf 5) or a random song from your favs (!srf).

Bonus points for giving either everyone or just the streamer the ability to see how much likes a song has. Could be fun to know.