fix(EventService): [AOU-557] prevent potential JPA exceptions by passing an id...

fix(EventService): [AOU-557] prevent potential JPA exceptions by passing an id instead of an entity through Spring event

https://issues.unige.ch/browse/AOU-557

AoU-Model/src/main/java/ch/unige/aou/model/notification/EventMessage.java

+package ch.unige.aou.model.notification;
+
+import ch.unige.aou.message.AouEntityMessage;
+
+public class EventMessage extends AouEntityMessage {
+  public EventMessage(String resId) {
+    super(resId);
+  }
+}