[PATCH v2 0/4] MR7332: mfreadwrite: Add tests for writer.

[Ziqing Hui (＠zhui)]

This is the refactoring of the tests in !7160. I submit a new seperate MR because I want to get the tests upstreamed first, otherwise making changes to tests patches needs rebasing the implementation patches. So plz review the tests MR first.

--
  v2: mfreadwrite/tests: Test sample processing for writer.
      mfreadwrite/tests: Test AddStream and SetInputMediaType for writer.
 
https://gitlab.winehq.org/wine/wine/-/merge_requests/7332