feature: Optimized Airplay Support

[ianclawson]

This PR implements Optimized AirPlay Support as per its Trello card.

There is a companion PR on Delta.

It's fully working and gets the feature just about there, minus a couple considerations noted below. Considerations are left unimplemented so as to keep this PR as small as possible.

Tested cases include:

• Default portrait and landscape skins on all current consoles (NES, SNES, GBC, GBA, N64, DS, GEN)
• Skins that act as overlays
• Skins that define a smaller, single screen (e.g. default landscape GBC)
• Rotation
• Entering/exiting mirroring
• External game controller attached/detached

Considerations:

• The sustain button view isn’t present on the mirrored screen, and no longer has the right constraints set once mirroring ends. Unsure if porting sustain over to the mirrored screen would be the right move to make or not
• When mirroring ends, I’m restoring gameView as a subview below controllerView. While that looked correct in my testing, it’s possible there is a more correct place elsewhere in the z-hierarchy that gameView should be that I have missed
• DS: currently this only mirrors the non-touch screen and leaves the touch screen on the iPhone screen. One day perhaps there could be a custom mirroring skin that allows for a larger touch screen when mirroring. That touches more code than I'm comfortable committing in this PR, so I leave that as an exercise for someone else 😉

NOTE: refer to the companion PR on Delta for the Settings toggle to enable the feature.

[zisko]

Awesome change!

[ianclawson]

Closing this to clean up my work list of Open PRs