build(aio): move doc-gen stuff from angular.io (#14097)

tools/docs/angular.io-package/mocks/importedSrc.ts

@@ -0,0 +1,9 @@
+/**
+ * @license
+ * Copyright Google Inc. All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+
+export const x = 100;