add test and implementation for addOrUpdate listeners

src/repositories/InMemoryNotificationRepository.ts

@@ -66,6 +66,19 @@ export class InMemoryNotificationRepository implements NotificationRepository {
     }
 
     this.deviceIdsToDeliverTo[tuple.toString()][deviceId] = secondsThreshold;
+    this.listeners.forEach((listener: Listener) => {
+      const event: NotificationEvent = {
+        event: 'addOrUpdate',
+        notification: {
+          shuttleId,
+          stopId,
+          deviceId,
+          secondsThreshold
+        },
+      }
+
+      listener(event);
+    })
   }
 
   async deleteNotificationIfExists({