Sends a VideoLayersAllocation header extension if frame rate change more than 5fps since the last time it was sent with valid frame rate and resolution. Bug: webrtc:12000 Change-Id: I2572c966025cc2c22743bbe2187cec7cceb86d01 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/234752 Reviewed-by: Danil Chapovalov <danilchap@webrtc.org> Commit-Queue: Per Kjellander <perkj@webrtc.org> Cr-Commit-Position: refs/heads/main@{#35180}