Use CVBufferGetAttachment or IOSurfaceGetYCbCrMatrix instead of hard coding the YCbCr matrix for GPUExternalTexture color conversion
<rdar://problem/111858329>
Pull request: https://github.com/WebKit/WebKit/pull/19016
Committed 269470@main (de69fde68bd5): <https://commits.webkit.org/269470@main> Reviewed commits have been landed. Closing PR #19016 and removing active labels.