refactor(compiler-cli): expose ngtools api separately (#18978)

PR Close #18978

packages/compiler-cli/ngtools2.ts

@@ -0,0 +1,8 @@
+/**
+ * @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 {CompilerHost, CustomTransformers, Diagnostic, EmitFlags, Program, createCompilerHost, createProgram, formatDiagnostics} from './src/ngtools_api2';