printers: Allow undoing deletion of a printer

Instead of directly applying the deletion of a printer, we should
follow the GNOME in-app notification deletion guidelines.

This patch introduces the in-app notification following the HIG[0]
for the deletion of a printer. It allows to "undo" the deletion.

The default behavior for these notification is to dismiss a previous
notification. In doing so, when deleting multiple printers, the
"Undo" button only restores the last deleted one. We don't do batch/
bulk removal in the printers panel.

[0] https://developer.gnome.org/hig/stable/in-app-notifications.html.en

https://bugzilla.gnome.org/show_bug.cgi?id=693187