Switch pkg packages, pub, and dartdoc to use package: imports.

utils/pub/pub.dart

Index: utils/pub/pub.dart
diff --git a/utils/pub/pub.dart b/utils/pub/pub.dart
index 1c05c45b977acf5a48f87bc588ea6d9741b4a09c..f94fa1456189de0ee3f67882895d2e55f18dea6a 100644
--- a/utils/pub/pub.dart
+++ b/utils/pub/pub.dart
@@ -9,8 +9,8 @@ import 'dart:async';
 import 'dart:io';
 import 'dart:math';
 
-import '../../pkg/args/lib/args.dart';
-import '../../pkg/pathos/lib/path.dart' as path;
+import 'package:args/args.dart';
+import 'package:pathos/path.dart' as path;
 
 import 'command_help.dart';
 import 'command_install.dart';