Unify the server and plugin versions of the generators

pkg/analysis_server/test/analysis/get_hover_test.dart

 // Copyright (c) 2014, 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.
 
 library test.domain.analysis.hover;
 
 import 'dart:async';
 
-import 'package:analysis_server/plugin/protocol/protocol.dart';
+import 'package:analysis_server/protocol/protocol.dart';
+import 'package:analysis_server/protocol/protocol_generated.dart';
 import 'package:test/test.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
 import '../analysis_abstract.dart';
 
 main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AnalysisHoverTest);
   });
 }
@@ skipping 502 matching lines @@
     addTestFile('''
 library my.library;
 main() {
   // nothing
 }
 ''');
     HoverInformation hover = await prepareHover('nothing');
     expect(hover, isNull);
   }
 }