Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/7974>
Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/7354>
Add a gstvkencoder class to support Vulkan encoder such as H26X formats. Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/6676>