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/windows/VideoPlayer/AutolinkedNativeModules.g.h

@@ -0,0 +1,10 @@
+// AutolinkedNativeModules.g.h contents generated by "react-native autolink-windows"
+// clang-format off
+#pragma once
+
+namespace winrt::Microsoft::ReactNative
+{
+
+void RegisterAutolinkedNativeModulePackages(winrt::Windows::Foundation::Collections::IVector<winrt::Microsoft::ReactNative::IReactPackageProvider> const& packageProviders);
+
+}