4.0.2 - Screen Sharing!

This update brings new classes and libraries for screen sharing!
See the detailed docs on how the screen sharing libraries work here:
https://agoraio-community.github.io/VideoUIKit-iOS/extensions/AgoraBroadcastExtensionHelper/

Smaller patch updates:

• Hide beautify button by default
• Disable Video UI Kit screen share button for iOS
• Showing all Video UI Kit submodule docs here: https://agoraio-community.github.io/VideoUIKit-iOS/extensions