There is currently no easy way for an application to distinguish between different resource write errors being set in the curlbasesink. Add curl status codes as error details on transfer failure. Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/4062>
gst_curl_base_sink_transfer_thread_close is moved from external header to be static function, as it has no users. Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/2732>