• Adds MediationExtras class to include parameters when using mediation through the implementation of FlutterMediationExtras in Android and FlutterMediationExtras in iOS.
• Deprecates MediationNetworkExtrasProvider and FLTMediationNetworkExtrasProvider.
• Removed the orientation parameter for the AppOpen Ad format.
• Bumps minimum Android SDK version to 21.
• Updates GMA iOS dependency to 11.2.0
• Updates GMA Android dependency to 23.0.0