add warning for deprecated .analysis_options file name

pkg/analyzer/lib/src/analysis_options/error/option_codes.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 analyzer.src.analysis_options.error.option_codes;
 
 import 'package:analyzer/error/error.dart';
 
 /**
  * The error codes used for errors in analysis options files. The convention for
@@ skipping 39 matching lines @@
 }
 
 /**
  * The error codes used for warnings in analysis options files. The convention
  * for this class is for the name of the error code to indicate the problem that
  * caused the error to be generated and for the error message to explain what is
  * wrong and, when appropriate, how the problem can be corrected.
  */
 class AnalysisOptionsWarningCode extends ErrorCode {
   /**
+   * An error code indicating the analysis options file name is deprecated
+   * and the file should be renamed.
+   *
+   * Parameters:
+   * 0: the uri of the file which should be renamed
+   */
+  static const ErrorCode DEPRECATED_ANALYSIS_OPTIONS_FILE_NAME =
+      const AnalysisOptionsWarningCode(
+          'DEPRECATED_ANALYSIS_OPTIONS_FILE_NAME',
+          "The name of the analysis options file {0} is deprecated."
+          " Consider renaming the file to analysis_options.yaml");
+
+  /**
    * An error code indicating a specified include file could not be found.
    *
    * Parameters:
    * 0: the uri of the file to be included
    * 1: the path of the file containing the include directive
    */
   static const AnalysisOptionsWarningCode INCLUDE_FILE_NOT_FOUND =
       const AnalysisOptionsWarningCode('INCLUDE_FILE_NOT_FOUND',
           "The include file {0} in {1} cannot be found.");
 
@@ skipping 72 matching lines @@
   const AnalysisOptionsWarningCode(String name, String message,
       [String correction])
       : super(name, message, correction);
 
   @override
   ErrorSeverity get errorSeverity => ErrorSeverity.WARNING;
 
   @override
   ErrorType get type => ErrorType.STATIC_WARNING;
 }