Revert "refactor(compiler-cli): expose ngtools api separately (#18952)"

This reverts commit 1953e2af7a.

packages/compiler-cli/ngtools2.ts

@@ -1,8 +0,0 @@
-/**
- * @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';