Unify the server and plugin versions of the generators

pkg/analysis_server/test/src/plugin/request_converter_test.dart

 // Copyright (c) 2017, 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 'package:analysis_server/plugin/protocol/protocol.dart' as server;
+import 'package:analysis_server/protocol/protocol_generated.dart' as server;
 import 'package:analysis_server/src/plugin/request_converter.dart';
 import 'package:analysis_server/src/protocol/protocol_internal.dart' as server;
 import 'package:analyzer_plugin/protocol/protocol_generated.dart' as plugin;
 import 'package:test/test.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
 import 'protocol_test_utilities.dart';
 
 main() {
   defineReflectiveSuite(() {
@@ skipping 103 matching lines @@
     int length = 3;
     String replacement = 'x';
     plugin.SourceEdit result = converter
         .convertSourceEdit(new server.SourceEdit(offset, length, replacement));
     expect(result, isNotNull);
     expect(result.offset, offset);
     expect(result.length, length);
     expect(result.replacement, replacement);
   }
 }