Add tests for Request Model

What does this mr do?

This MR adds tests for the Request model

src/main/java/nl/tudelft/ewi/queue/model/Request.java

@@ -738,7 +738,7 @@ public class Request implements RecordsEvents<Request>, Serializable, Comparable
 		return requests;
 	}
 
-	private Boolean displayRequest() {
+	public Boolean displayRequest() {
 		if (!this.getLab().isSignOffIntervals()) {
 			return true;
 		}