Rewrite iOS AR Camera in Swift

[albullington]

I started exploring a Swift RN camera here, but it would be helpful for someone else to pick this up and run with it. The new RN-vision-camera library is written in Swift and might have some example code we can use.

The reasons we want to rewrite this in Swift are:

1. Swift is more similar to RN than Obj-C, which means it might be easier to have non-native developers help maintain this library. Additionally, there are a lot more recent tutorials / resources on the web teaching people how to write camera code in Swift.
2. Swift now works with RN (it didn't when we first wrote this library)
3. We can incorporate frame processors, which seem to be the way forward for achieving native performance in a JS app.