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>