Add mime type mapping to enable the use of Android H.265 encoders Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/2511>
When copying data out of a GStreamer buffer, we don't need to map it writable. Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/2492>