iOS Swift Conversion (#2527)

Converts iOS implementation from Objective-c to Swift

# During the conversion process some updates to the code structure were also made
- Modularize codebase from single file to smaller focused files
- Untangled large nested IF statements
- Added more null checks, since Swift is more strict with null pointers
- Added property to allow for decoding of local video sources with self contained key for offline playback
- Updates example apps to test react-native 0.63.4 and uses auto native dependency imports for android and ios

ios/Video/RCTVideoPlayerViewControllerDelegate.swift

@@ -0,0 +1,7 @@
+import Foundation
+import AVKit
+
+protocol RCTVideoPlayerViewControllerDelegate : NSObject {
+    func videoPlayerViewControllerWillDismiss(playerViewController:AVPlayerViewController)
+    func videoPlayerViewControllerDidDismiss(playerViewController:AVPlayerViewController)
+}