Remove uses of the old plugin model from the analysis server

pkg/analysis_server/lib/plugin/analysis/analyzed_files.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.
-
-/**
- * Support for client code that extends the set of files being analyzed by the
- * analysis server.
- *
- * Plugins can contribute a list of file patterns. Any file whose path matches
- * one or more of the contributed patterns will be analyzed. The file patterns
- * are interpreted as glob patterns as defined by the 'glob' package.
- *
- * If a plugin is interested in analyzing a certain kind of file, it needs to
- * ensure that files of that kind will be analyzed. It should register a list of
- * file patterns by including code like the following in the plugin's
- * registerExtensions method:
- *
- *     @override
- *     void registerExtensions(RegisterExtension registerExtension) {
- *       ...
- *       registerExtension(
- *           ANALYZED_FILE_PATTERNS_EXTENSION_POINT_ID,
- *           ['*.yaml']);
- *       ...
- *     }
- */
-import 'package:analysis_server/src/plugin/server_plugin.dart';
-import 'package:plugin/plugin.dart';
-
-/**
- * The identifier of the extension point that allows plugins to cause certain
- * kinds of files to be analyzed. The object used as an extension must be a list
- * of strings. The strings are interpreted as glob patterns as defined by the
- * 'glob' package.
- */
-final String ANALYZED_FILE_PATTERNS_EXTENSION_POINT_ID = Plugin.join(
-    ServerPlugin.UNIQUE_IDENTIFIER,
-    ServerPlugin.ANALYZED_FILE_PATTERNS_EXTENSION_POINT);