chore: add rosetta to example construct library (aws#19498)

----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

Author: kaizencc

packages/@aws-cdk/example-construct-library/rosetta/default.ts-fixture

@@ -0,0 +1,11 @@
+// Fixture with packages imported, but nothing else
+import { Construct } from 'constructs';
+import { Stack } from '@aws-cdk/core';
+
+class Fixture extends Stack {
+  constructor(scope: Construct, id: string) {
+    super(scope, id);
+
+    /// here
+  }
+}