Move pub into sdk/lib/_internal.

sdk/lib/_internal/pub/test/lish/force_cannot_be_combined_with_dry_run_test.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. 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:json' as json;
 
 import 'package:scheduled_test/scheduled_test.dart';
 import 'package:scheduled_test/scheduled_server.dart';
 
-import '../../../pub/exit_codes.dart' as exit_codes;
+import '../../lib/src/exit_codes.dart' as exit_codes;
 import '../descriptor.dart' as d;
 import '../test_pub.dart';
 import 'utils.dart';
 
 main() {
   initConfig();
   setUp(d.validPackage.create);
 
   integration('--force cannot be combined with --dry-run', () {
     schedulePub(args: ['lish', '--force', '--dry-run'],
         error: "Cannot use both --force and --dry-run.",
         exitCode: exit_codes.USAGE);
   });
 }