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/MainPage.xaml

@@ -0,0 +1,16 @@
+<Page
+    x:Class="videoplayer.MainPage"
+    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+    xmlns:local="using:videoplayer"
+    xmlns:react="using:Microsoft.ReactNative"
+    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+    mc:Ignorable="d"
+    Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
+    <react:ReactRootView 
+        x:Name="ReactRootView"
+        ComponentName="VideoPlayer"
+        Background="{ThemeResource ApplicationPageBackgroundThemeBrush}"
+        MinHeight="400"/>
+</Page>