Moves everything Camera related into `core/` / `Core/` so that it is better encapsulated from React Native.
Benefits:
1. Code is much better organized. Should be easier for collaborators now, and cleaner codebase for me.
2. Locking is fully atomically as you can now only configure the session through a lock/Mutex which is batch-overridable
* On iOS, this makes Camera startup time **MUCH** faster, I measured speedups from **1.5 seconds** to only **240 milliseconds** since we only lock/commit once! 🚀
* On Android, this fixes a few out-of-sync/concurrency issues like "Capture Request contains unconfigured Input/Output Surface!" since it is now a single lock-operation! 💪
3. It is easier to integrate VisionCamera outside of React Native (e.g. Native iOS Apps, NativeScript, Flutter, etc)
With this PR, VisionCamera V3 is up to **7x** faster than V2
