Remove the command-line plugin

pkg/analyzer/lib/plugin/command_line.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 command-line tools that use the analysis
- * engine by adding new command-line arguments.
- */
-library analyzer.plugin.command_line;
-
-import 'package:analyzer/src/plugin/command_line_plugin.dart';
-import 'package:args/args.dart';
-import 'package:plugin/plugin.dart';
-
-/**
- * The identifier of the extension point that allows plugins to add new flags
- * and options to the command-line parser before the parser is used to parse
- * the command-line. The object used as an extension must be an
- * [ArgParserContributor].
- */
-final String PARSER_CONTRIBUTOR_EXTENSION_POINT_ID = Plugin.join(
-    CommandLinePlugin.UNIQUE_IDENTIFIER,
-    CommandLinePlugin.PARSER_CONTRIBUTOR_EXTENSION_POINT);
-
-/**
- * The identifier of the extension point that allows plugins to access the
- * result of parsing the command-line. The object used as an extension must be
- * an [ArgResultsProcessor].
- */
-final String RESULT_PROCESSOR_EXTENSION_POINT_ID = Plugin.join(
-    CommandLinePlugin.UNIQUE_IDENTIFIER,
-    CommandLinePlugin.RESULT_PROCESSOR_EXTENSION_POINT);
-
-/**
- * A function that will contribute flags and options to the command-line parser.
- */
-typedef void ArgParserContributor(ArgParser parser);
-
-/**
- * A function that will process the results of parsing the command-line.
- */
-typedef void ArgResultsProcessor(ArgResults results);