Implementing FrameSinkDesktopCapturer

FrameSinkDesktopCapturer is implemented and added to the flow of capturing frames for the flow of Chrome Remote Desktop for Chrome OS.

Design Doc: https://docs.google.com/document/d/e/2PACX-1vQksleLXuZkie4X32aYpo9Mu9gy6hBFrQ-iF7w8KfzM28Tk_Crsfd45HZhoDpn4nqllnoYDcMkI5Mrq/pub

Bug: b/236819144
Test: Added Unittest ( FrameSinkDesktopCapturerUnittest ).
Change-Id: I00b988b99869129d8ee432ef553a9cd7034604fd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3724369


Reviewed-by: Thomas Guilbert <tguilbert@chromium.org>
Reviewed-by: Joe Downing <joedow@chromium.org>
Reviewed-by: Jeroen Dhollander <jeroendh@google.com>
Reviewed-by: Kyle Charbonneau <kylechar@chromium.org>
Commit-Queue: Ashutosh Singhal <macinashutosh@google.com>
Cr-Commit-Position: refs/heads/main@{#1044515}