mediacodec: refactor StartMediaCodec
mediacodec: refactor StartMediaCodec

Add ParseVideoExtra that parse video extra data for h264/hevc.
Leave room for a possible ParseAudioExtra.

shyamalschandra/vlc,xkfz007/vlc,vlc-mirror/vlc,shyamalschandra/vlc,shyamalschandra/vlc,xkfz007/vlc,shyamalschandra/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,vlc-mirror/vlc,shyamalschandra/vlc,vlc-mirror/vlc,xkfz007/vlc,vlc-mirror/vlc,vlc-mirror/vlc,shyamalschandra/vlc,vlc-mirror/vlc,xkfz007/vlc,vlc-mirror/vlc,shyamalschandra/vlc