This new metadata API allows elements to attach LCEVC enhancement data to video
buffers. Usually, the video parser elements are charged to parse the LCEVC
enhancement data from SEI Nal units (Supplemental enhancement Information).
However, other elements such as demuxers can also use this API if the LCEVC
enhancement data of the video is stored in a separate stream in the container.
Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/7330>
