Deprecate the generated AST library and clean up imports

pkg/analysis_server/lib/src/provisional/edit/utilities/change_builder_dart.dart

 // Copyright (c) 2015, 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 analysis_server.plugin.edit.utilities.change_builder_dart;
 
 import 'package:analysis_server/src/provisional/edit/utilities/change_builder_core.dart';
 import 'package:analysis_server/src/utilities/change_builder_dart.dart';
+import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/dart/element/type.dart';
-import 'package:analyzer/src/generated/ast.dart';
 import 'package:analyzer/src/generated/engine.dart';
 
 /**
  * A [ChangeBuilder] used to build changes in Dart files.
  *
  * Clients may not extend, implement or mix-in this class.
  */
 abstract class DartChangeBuilder extends ChangeBuilder {
   /**
    * Initialize a newly created change builder.
@@ skipping 126 matching lines @@
       String groupName,
       bool required: false});
 }
 
 /**
  * A [FileEditBuilder] used to build edits for Dart files.
  *
  * Clients may not extend, implement or mix-in this class.
  */
 abstract class DartFileEditBuilder extends FileEditBuilder {}