libaom supports for NV12 inputs for encoding av1 stream. It will reduce unnecessary conversion from NV12 to I420 format. (https://bugs.chromium.org/p/aomedia/issues/detail?id=3232&q=3232&can=2) Bug: webrtc:13746 Change-Id: I1407227d1690b3f63cb6581eef5d587e5f418892 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/251920 Reviewed-by: Erik Språng <sprang@webrtc.org> Reviewed-by: Ilya Nikolaevskiy <ilnik@webrtc.org> Commit-Queue: Shuhai Peng <shuhai.peng@intel.com> Cr-Commit-Position: refs/heads/main@{#36111}