Rationalize GNOME credit button handling
    
    We had a ton of needles all covering something very similar
    (press a "Credits" button in a GNOME app). There are about four
    real variations: old-style regular face white-on-black (eog),
    old-style regular face (nautilus and evince before recent
    libadwaita ports), old-style bold face (GTE and Clocks before
    new libadwaita), and new-style (everything that's been ported
    to use libadwaita for its About page). Let's just rationalize
    it down to those, using the same needle tag for all of them.
    
    Signed-off-by: Adam Williamson <awilliam@redhat.com>