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

examples/basic/src/VideoPlayer.windows.tsx

@@ -212,4 +212,4 @@ const styles = StyleSheet.create({
     justifyContent: 'center',
   },
 });
-export default VideoPlayer
+export default VideoPlayer