This helper class currently lives in `modules/video_coding`, but it's only users are in `video/`. Thus, it makes sense to move the class to `video/`. Bug: webrtc:14116 Change-Id: I0d3f8961bc8f5fe80f3100dbbd309b206020e6d5 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/262963 Reviewed-by: Åsa Persson <asapersson@webrtc.org> Commit-Queue: Rasmus Brandt <brandtr@webrtc.org> Cr-Commit-Position: refs/heads/main@{#36973}