mfvideoenc: Add support for ROI videometa
Similar to ROI + delta-qp implementation in msdk and vaapi, mediafoundation
video encoder can support delta-qp for ROI.
See https://docs.microsoft.com/en-us/windows/win32/medfound/codecapi-avencvideoroienabled and https://docs.microsoft.com/en-us/windows/win32/medfound/mfsampleextension-roirectangle