Get rid of SFBAudioPlayer (SBPlayer.localPlayer)

[NattyNarwhal]

The counterpart to GH-54.

Right now, we do load SFBAudioPlayer, but it's nopped out, because it seems to have difficulty playing well together with AVPlayer.

Benefits of keeping and getting it working:

• Better format support
• More flexible interface

Getting rid of it:

• Doesn't do HTTP without pain, meaning we likely need to defer to AVPlayer
• Massively reduces binary size
• Simplifies build system
• Formats it supports are unlikely to be in a Subsonic server anyways, since nowadays Core Audio does Vorbis/FLAC
  • Maybe DSD, Monkey, Musepack?
  • And those formats can't be streamed, so it's likely that AVPlayer needs to do the work (or Subsonic server can transcode)
• Has issues with spatialized audio (doesn't support it without effort?)
• Will have to implement things like AVRoutePickerView's or SharePlay's delegate ourself

[NattyNarwhal]

It might be worth keeping the infrastructure for a theoretical jukebox mode (server plays audio).