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/android/app/src/main/res/values/styles.xml

@@ -3,6 +3,7 @@
     <!-- Base application theme. -->
     <style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">
         <!-- Customize your theme here. -->
+        <item name="android:textColor">#000000</item>
     </style>
 
 </resources>