Moves FrameBuffer2 to its own GN target to reduce the binary size of the video target. Bug: None Change-Id: I40e86a1eabc0c9e8e6fada3dcdb4e3a043c61c6c Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/271286 Commit-Queue: Evan Shrubsole <eshr@webrtc.org> Reviewed-by: Erik Språng <sprang@webrtc.org> Cr-Commit-Position: refs/heads/main@{#37803}