feat(notifications): add notification display rules

- block: skips the notification completely
- mute: does not play sound (played by noctalia), shows popup, adds to
history
- hide: no sound, no popup, still adds to history

shell.qml

@@ -112,6 +112,7 @@ ShellRoot {
           IdleService.init();
           PowerProfileService.init();
           HostService.init();
+          NotificationRulesService.init();
           GitHubService.init();
           SupporterService.init();
           CustomButtonIPCService.init();