At least for the time being, this looks like the easiest option to
launch the service:
- we could add a systemd unit, but then we'd need to update the
RequiredComponents in the fallback session definition as well,
making it necessary for gnome-shell, gnome-shell-extensions and
gnome-session to be updated to 3.36.1 in lockstep
- autostart is problematic as it would make gnome-shell conflict
with other notification daemons; also autostart is most useful
with automatic shutdown, which would require tracking signal
subscriber to determine when the service is unused
https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/547
f2df347ddb