The h26xdecoder 'stop' method was not called
as the vulkan h26x class rewires the video decoder
'stop' base method to its own one.
It was causing some memory leaks such as dangling parser
and dpb in h26xdecoder base class.
Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/6787>
The pool currently defaults to performing a layout transition to
VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL, with some special exceptions for
video usages. This may not be a legal transition depending on the usage.
Provide an API to explicitly control the initial image layout.
Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/5881>
