refactor(compiler): remove unused CachedFileSystem (#36687)

This was only being used by ngcc but not any longer.

PR Close #36687

packages/compiler-cli/src/ngtsc/file_system/index.ts

@@ -5,7 +5,6 @@
  * 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 {CachedFileSystem} from './src/cached_file_system';
 export {NgtscCompilerHost} from './src/compiler_host';
 export {absoluteFrom, absoluteFromSourceFile, basename, dirname, getFileSystem, isRoot, isRooted, join, relative, relativeFrom, resolve, setFileSystem} from './src/helpers';
 export {LogicalFileSystem, LogicalProjectPath} from './src/logical';