Since y4menc inherits from GstVideoEncoder, it negotiates upstream buffer pools
with GstVideoMeta support. Thus, certain decoders might use that meta for
frames with padded memory. Nonetheless y4menc assumes only linear memory video
frames, without padding.
This patch will copy frames using gst_video_frame_copy() if buffer has
GstVideoMeta or its video info is padded with its custom video info. Otherwise,
it ill call the agnostic gst_buffer_copy() for a shallow copy.
Supersedes: !5042Fixes: #2765
Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/8654>
