Resolve "Notify students when they cannot be found by TA"

What does this mr do?

This mr adds a new not found notification. Students will receive this notification if the TA clicks the 'not found' button.

Screenshots

before

after

Does this MR meet the acceptance criteria?

• I have added a changelog entry to reflect the significant changes I made.
• Tests were created to test the feature.
• I have updated the documentation accordingly.
• I adhere to the style guide.
  Closes #245 (closed)

src/main/java/nl/tudelft/ewi/queue/service/NotificationService.java

@@ -138,4 +138,22 @@ public class NotificationService {
 		return notifications;
 	}
 
+	public Map<User, Notification> createNotFoundNotification(RequestEntity requestEntity, Request request) {
+		Map<User, Notification> notifications = new HashMap<>();
+		if (requestEntity.isGroup()) {
+			for (User user : ((Group) requestEntity).getMembers()) {
+				notifications.put(user, new Notification(user,
+						request.getLab().getCourse(), "Not Found",
+						"The TA was not able to find you. Please check if you filled in the correct room!",
+						100));
+			}
+		} else {
+			notifications.put((User) requestEntity, new Notification((User) requestEntity,
+					request.getLab().getCourse(), "Not Found",
+					"The TA was not able to find you. Please check if you filled in the correct room! Remember to respond to the TA when he/she calls your name!",
+					100));
+		}
+		return notifications;
+	}
+
 }