Draft: mpegts: Add provisional AV1 mapping
The main difference with the WIP av1-in-mpegts mapping is that the payload data is not startcode-escaped. Most of the rest is sensible usage of it:
- Custom AV1G (AV1 Gstreamer) registration descriptor instead of AV01
- AV1CodecConfigurationRecord is stored in the same 0x80 custom descriptor and conforms fully to the isobmff spec (i.e. does not the HDR fields from the provisional mpegts specification which conflict with that one).
- Data is stored as OBU
- Access Unit is the frame level (same as provisional mpegts mapping)