Add GStreamer formats

[emersion]

Not yet clear to me which endianness they use.

[emersion]

The list is here: https://gitlab.freedesktop.org/gstreamer/gst-plugins-base/-/blob/f886766a6bdd8abd4145ab8016e3190748b9fcc2/gst-libs/gst/video/video-format.c#L6570

The formats in general lay out the components in big-endian order. Except for some formats guarded by #ifdefs such as RGB16.

The docs go into great detail but still omit this information: https://gstreamer.freedesktop.org/documentation/additional/design/mediatype-video-raw.html?gi-language=c#formats