Boxes dropped VNC functionality. It's supposed to be replaced by
Connections, but we can't use that until it has fullscreen:
https://gitlab.gnome.org/GNOME/connections/-/issues/5
so use Vinagre for now. We do also prepare some needles for
Connections in anticipation of being able to use it later (since
I already did the work and don't want to waste it...)
Signed-off-by: Adam Williamson <awilliam@redhat.com>
