Based on top of tests MR !7125.
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v2: mfreadwrite: Implement IMFSinkWriterEx.
mfreadwrite: Implement create_transform.
mfreadwrite: Implement sink_writer_SetInputMediaType.
mfreadwrite: Rename update_media_type_from_upstream and make it non-static.
mfreadwrite: Use a transform array for writer.
mfreadwrite/tests: Test sample processing for mp4 sink writer.
mfreadwrite/tests: Test getting transforms from mp4 sink writer.
mfreadwrite/tests: Test AddStream and SetInputMediaType for mp4 sink writer.
mfreadwrite/tests: Remove trivial if.
https://gitlab.winehq.org/wine/wine/-/merge_requests/7160