Similar to h264parse, this patch enhances the element to parse LCEVC enhancement
data from SEI, and attach it to output buffers as GstLcevcMeta. The 'lcevc'
field in the output caps is also set to TRUE or FALSE depending on whether LCEVC
data is present or not.
Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/9335>