mpegvideoparse: Expose colorimetry into the caps

This is a reminder for myself, but if someone wants to pick it up it is really simple. The parser already parsers the colorimetry information from the stream, I think it would be nice to translate it and expose it.

• Add enums of the mpeg2 primaries, transfer and matrix values in codecparsers
• Map and expose colorimetry in mpegvideoparse element

An optional task would be to find what defaults are suppose to be used for each video_format (PAL, NTSC, SECAM, MAC) and set some defaults base on that, unless of course GstVideoInfo already get it right without that bitstream information. This is all of course if the demuxer didn't expose.

Special case to considered, demuxers tends to leave some value to 0, unknown, it would be nice to fill the gap in the parser if known.