Revert of Move CoreVideoFrameBuffer from webrtc/common_video/ to webrtc/sdk/objc/ (patchset #2 id:60001 of https://codereview.webrtc.org/2851563003/ )

Reason for revert:
Breaks downstream targets.

Original issue's description:
> Move CoreVideoFrameBuffer from webrtc/common_video/ to webrtc/sdk/objc/
>
> CoreVideoFrameBuffer is Mac/iPhone specific and should be moved into
> the webrtc/sdk/objc/ folder.
>
> BUG=None
>
> Review-Url: https://codereview.webrtc.org/2851563003
> Cr-Commit-Position: refs/heads/master@{#17998}
> Committed: d41631aa27

TBR=kthelgason@webrtc.org,magjed@webrtc.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=None

Review-Url: https://codereview.webrtc.org/2862663003
Cr-Commit-Position: refs/heads/master@{#18004}

webrtc/sdk/objc/Framework/Classes/RTCVideoFrame.mm

@@ -10,7 +10,7 @@
 
 #import "RTCVideoFrame+Private.h"
 
-#include "webrtc/sdk/objc/Framework/Classes/corevideo_frame_buffer.h"
+#include "webrtc/common_video/include/corevideo_frame_buffer.h"
 
 @implementation RTCVideoFrame {
   rtc::scoped_refptr<webrtc::VideoFrameBuffer> _videoBuffer;