fix(bazel): flat module misses AMD module name on windows (#27839)

* Fixes that the flat module out files do not have a proper AMD module name on Windows. This is currently blocking serving a `ng_module` using the Bazel TypeScript `devserver` on Windows.

PR Close #27839

packages/bazel/test/ngc-wrapped/flat_module/export.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 Test = 'This is a test export';