[AVFoundation] Improve AVPlayerItemVideoOutput.CopyPixelBuffer. Fixes #21702. (#21710)

* The generator can handle the custom logic now, so remove the manually written bindings.
* Add the API for macOS.

Fixes #21702.

Author: rolfbjarne

src/AVFoundation/AVPlayer.cs

@@ -13823,9 +13823,18 @@ interface AVPlayerItemVideoOutput {
 		[Export ("hasNewPixelBufferForItemTime:")]
 		bool HasNewPixelBufferForItemTime (CMTime itemTime);
 
+#if !XAMCORE_5_0
 		[Protected]
 		[Export ("copyPixelBufferForItemTime:itemTimeForDisplay:")]
 		IntPtr WeakCopyPixelBuffer (CMTime itemTime, ref CMTime outItemTimeForDisplay);
+#endif
+
+#if !XAMCORE_5_0
+		[Sealed]
+#endif
+		[Export ("copyPixelBufferForItemTime:itemTimeForDisplay:")]
+		[return: Release]
+		CVPixelBuffer CopyPixelBuffer (CMTime itemTime, ref CMTime outItemTimeForDisplay);
 
 		[Export ("setDelegate:queue:")]
 		void SetDelegate ([NullAllowed] IAVPlayerItemOutputPullDelegate delegateClass, [NullAllowed] DispatchQueue delegateQueue);

src/avfoundation.cs

@@ -281,7 +281,6 @@ AVFOUNDATION_SOURCES = \
 	AVFoundation/AVMetadataMachineReadableCodeObject.cs \
 	AVFoundation/AVMetadataObject.cs \
 	AVFoundation/AVOutputSettingsAssistant.cs \
-	AVFoundation/AVPlayer.cs \
 	AVFoundation/AVPlayerItem.cs \
 	AVFoundation/AVPlayerItemVideoOutput.cs \
 	AVFoundation/AVPlayerLayer.cs \