feat(bazel): ng_module produces bundle index (#22176)

It creates the bundle index .d.ts and .metadata.json files.
The names are based on the ng_module target.

PR Close #22176

packages/compiler-cli/integrationtest/bazel/ng_module/spec.js

@@ -0,0 +1,31 @@
+/**
+ * @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
+ */
+
+const fs = require('fs');
+const PKG = 'angular/packages/compiler-cli/integrationtest/bazel/ng_module';
+describe('flat module index', () => {
+  describe('child metadata', () => {
+    it('should have contents', () => {
+      const metadata = fs.readFileSync(
+          require.resolve(`${PKG}/_test_module.bundle_index.metadata.json`), {encoding: 'utf-8'});
+      expect(metadata).toContain('"__symbolic":"module"');
+      expect(metadata).toContain('"__symbolic":"reference","module":"@angular/core"');
+      expect(metadata).toContain('"origins":{"Child":"./child","ɵa":"./parent"}');
+      expect(metadata).toContain('"importAs":"some_npm_module"');
+    });
+  });
+  describe('child typings', () => {
+    it('should have contents', () => {
+      const dts = fs.readFileSync(
+          require.resolve(`${PKG}/_test_module.bundle_index.d.ts`), {encoding: 'utf-8'});
+
+      expect(dts).toContain('export * from \'./index\';');
+      expect(dts).toContain('export { Parent as ɵa } from \'./parent\';');
+    });
+  });
+});