feat(user-sessions): implement GameLobby and user session management with exception handling

knockoutwhistweb/app/exceptions/NotInteractableException.java

@@ -0,0 +1,7 @@
+package exceptions;
+
+public class NotInteractableException extends RuntimeException {
+    public NotInteractableException(String message) {
+        super(message);
+    }
+}