Adding directives_ordering (#396)

platform_design/analysis_options.yaml

@@ -15,6 +15,7 @@ linter:
     - close_sinks
     - constant_identifier_names
     - control_flow_in_finally
+    - directives_ordering
     - empty_statements
     - hash_and_equals
     - implementation_imports

platform_design/lib/main.dart

@@ -1,10 +1,10 @@
 import 'package:flutter/cupertino.dart';
 import 'package:flutter/material.dart';
 
-import 'songs_tab.dart';
 import 'news_tab.dart';
 import 'profile_tab.dart';
 import 'settings_tab.dart';
+import 'songs_tab.dart';
 import 'widgets.dart';
 
 void main() => runApp(MyAdaptingApp());