Add functionality for dumping encoder and decoder input to file in video codec test. Bug: b/261160916, webrtc:14852 Change-Id: I49a84a886d87903c601cf5c35bd723b6393c2a75 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/298051 Commit-Queue: Sergey Silkin <ssilkin@webrtc.org> Reviewed-by: Erik Språng <sprang@webrtc.org> Cr-Commit-Position: refs/heads/main@{#39626}