video: add VUYA pixel format

video: add VUYA pixel format

AYUV in gstreamer was defined in A-Y-U-V order in memory[1], however
Microsoft defined another AYUV format in V-U-Y-A order in memory[2]. Add
VUYA format for the latter in order to distinguish the two formats

[1] https://gstreamer.freedesktop.org/documentation/design/mediatype-video-raw.html#formats
[2] https://docs.microsoft.com/en-us/windows/desktop/medfound/recommended-8-bit-yuv-formats-for-video-rendering#ayuv)