Refresh quietly from the path unit and pacman hook

Add a --quiet mode that updates the pending file without notifying, run by
the new update-notify-quiet.service, so aur sync doesn't notify per package.

update-notify-refresh

@@ -6,5 +6,5 @@ while read -r unit _; do
     uid=${uid%.service}
     user=$(id -nu "$uid") || continue
     systemctl --user -M "$user@" is-active --quiet update-notify.timer || continue
-    systemctl --user -M "$user@" start --no-block update-notify.service
+    systemctl --user -M "$user@" start --no-block update-notify-quiet.service
 done