fix(cdk-experimental/clipboard): add missing tsconfig (#16785)

(cherry picked from commit 6fe8c06)

Author: mmalerba

src/cdk-experimental/clipboard/index.ts

@@ -0,0 +1,9 @@
+/**
+ * @license
+ * Copyright Google LLC 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 * from './public-api';

src/cdk-experimental/clipboard/public-api.ts

@@ -0,0 +1,11 @@
+/**
+ * @license
+ * Copyright Google LLC 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 * from './clipboard';
+export * from './clipboard-module';
+export * from './copy-to-clipboard';

src/cdk-experimental/clipboard/tsconfig-build.json

@@ -0,0 +1,15 @@
+{
+  "extends": "../tsconfig-build",
+  "files": [
+    "public-api.ts",
+    "../typings.d.ts"
+  ],
+  "angularCompilerOptions": {
+    "annotateForClosureCompiler": true,
+    "strictMetadataEmit": true,
+    "flatModuleOutFile": "index.js",
+    "flatModuleId": "@angular/cdk-experimental/clipboard",
+    "skipTemplateCodegen": true,
+    "fullTemplateTypeCheck": true
+  }
+}