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

CHANGELOG.md

@@ -14,6 +14,9 @@
 - (Breaking) Bump shaka-player to 3.3.2 [#2587](https://github.com/react-native-video/react-native-video/pull/2587)
 - Improve basic player example on android [#2662](https://github.com/react-native-video/react-native-video/pull/2662)
 - Ensure we always use `hideShutterView` before showing the `shutterView` on Android [#2609](https://github.com/react-native-video/react-native-video/pull/2609)
+- Convert iOS implementation to Swift [#2527](https://github.com/react-native-video/react-native-video/pull/2527)
+- Add iOS support for decoding offline sources [#2527](https://github.com/react-native-video/react-native-video/pull/2527)
+- Update basic example applications (React Native 0.63.4) [#2527](https://github.com/react-native-video/react-native-video/pull/2527)
 
 ### Version 5.2.0
 
@@ -223,4 +226,4 @@
 - Add cookie support for ExoPlayer [#922](https://github.com/react-native-community/react-native-video/pull/922)
 - Remove ExoPlayer onMetadata that wasn't being used [#1040](https://github.com/react-native-community/react-native-video/pull/1040)
 - Fix bug where setting the progress interval on iOS didn't work [#800](https://github.com/react-native-community/react-native-video/pull/800)
-- Support setting the poster resize mode [#595](https://github.com/react-native-community/react-native-video/pull/595)
+- Support setting the poster resize mode [#595](https://github.com/react-native-community/react-native-video/pull/595)