Move terminal example from //sky/examples to //examples

examples/terminal/terminal_file_impl.dart

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 import 'dart:async';
 import 'dart:core';
 import 'package:mojo/public/dart/core.dart';
 import 'package:mojo/services/files/public/interfaces/file.mojom.dart' as files;
 import 'package:mojo/services/files/public/interfaces/types.mojom.dart' as files;
 
@@ skipping 104 matching lines @@
     // TODO(vtl)
     return responseFactory(files.Error_UNIMPLEMENTED);
   }
 
   @override
   Future asBuffer(Function responseFactory) async {
     // TODO(vtl)
     return responseFactory(files.Error_UNIMPLEMENTED, null);
   }
 }