Adds crop-x, crop-y, crop-width, crop-height properties specifying the screen area to capture. Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/1932>
Old name "desktopdup" may confuse users. Now it's renamed to "screencapture" Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/1136>