Encoded Frames now have VideoRotation data

In order to grab this data in the Webm Muxer in chromium source code, we
need to add a Video Rotation method on Encoded frames (similar to how we
grab color space metadata). This CL adds this method, but returns
std::nullopt. Once this change is rolled in chromium source code, I can
update a chromium dependency to use this method, then make a following
CL to `=0;` rather than return std::nullopt.

Bug: chromium:391786486
Change-Id: I4e98a9c6243849d4815449a0e8410f971ddc2ad1
No-Iwyu: Ran tools_webrtc/iwyu/apply-include-cleaner but nothing changed
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/382060
Reviewed-by: Erik Språng <sprang@webrtc.org>
Reviewed-by: Per Kjellander <perkj@webrtc.org>
Commit-Queue: Syed AbuTalib <lowkey@google.com>
Cr-Commit-Position: refs/heads/main@{#44343}