gnome-shell depends on gdm's client library at runtime, but the
new pipeline-built image no longer provides it.
Add it back, but built it from source instead of using the Fedora
package, so we don't draw in all of gdm's runtime dependencies
(which includes a full GNOME session including gnome-shell).
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1590>
