WIP adding music

[Giesch]

Adds basic effects for music streams. This comes with a few caveats:

1. we leak music streams (like everything else); properly cleaning them up might need a new helper in roc
   https://roc.zulipchat.com/#narrow/channel/304641-ideas/topic/Host.20iteration.20access.20to.20roc.20resource.20heaps/near/479104637
2. There's a nonsense Str error type in getMusicTimePlayed; this is working around the void tag compiler bug
3. the 'restarting while paused' case in the example is weird because of a raylib issue;
   it looks like their example (or their music api?) has a bug where progress doesn't get reset,
   stopping a paused track resets the actual audio but not the played length

Also, the various music effects mostly share the permission enum for PlayMusic