Support Spectator protocol and/or Menu Frame

https://github.com/project-slippi/slippi-wiki/blob/master/SPECTATOR_PROTOCOL.md

https://github.com/project-slippi/slippi-wiki/pull/16

This could be used to broadcast to a local program providing a faster live feed of a game. I haven't really thought about this further, but I think it's something peppi should do eventually.