Restructure the public API for server

pkg/analysis_server/lib/plugin/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 register a function that takes a [File] and returns a [bool]
- * indicating whether the plugin is interested in having that file be analyzed.
- * The analysis server will invoke the contributed functions and analyze the
- * file if at least one of the functions returns `true`. (The server is not
- * required to invoke every function with every file.)
- *
- * If a plugin is interested in analyzing a certain kind of files, it needs to
- * ensure that files of that kind will be analyzed. It should register a
- * function by including code like the following in the plugin's
- * registerExtensions method:
- *
- *     @override
- *     void registerExtensions(RegisterExtension registerExtension) {
- *       ...
- *       registerExtension(
- *           ANALYZE_FILE_EXTENSION_POINT_ID,
- *           (File file) => file.path.endsWith(...));
- *       ...
- *     }
- */
-library analysis_server.plugin.analyzed_files;
-
-import 'package:analysis_server/src/plugin/server_plugin.dart';
-import 'package:analyzer/file_system/file_system.dart';
-import 'package:plugin/plugin.dart';
-
-/**
- * The identifier of the extension point that allows plugins to register
- * functions that can cause files to be analyzed. The object used as an
- * extension must be a [ShouldAnalyzeFile] function.
- */
-final String ANALYZE_FILE_EXTENSION_POINT_ID = Plugin.join(
-    ServerPlugin.UNIQUE_IDENTIFIER, ServerPlugin.ANALYZE_FILE_EXTENSION_POINT);
-
-/**
- * A function that returns `true` if the given [file] should be analyzed.
- */
-typedef bool ShouldAnalyzeFile(File file);