media: add video recording support

If there are 2 video streams, overlays local video over peer video. Peer
video will be upscaled if it is too small, while local video will be
scaled to 1/16th the size of the peer video.

If there is only 1 video stream, uses peer video settings if they are
valid, or fall back on local video settings.

Adds title and description metadata to recorded file.

Change-Id: I182de013e3ac2d18161eadf406fc6494e5f59a4e