vaapidecode: expose raw src caps with same chroma

vaapidecode: expose raw src caps with same chroma

The try-and-error approach for getting the possible image formats from
a surface has brought several problems in different drivers, from
crashes to drop in performance.

Instead of that we change the algorithm to determine the possible
image formats based in the surface chroma: only those available image
formats with same chroma are exposed as possible raw caps.

Do this is important to avoid performance degrading in raw sinks
which doesn't handle NV12 but it does YV12 or I420.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer-vaapi/-/merge_requests/381>