Adding in an edit icon on the action header

Summary: Test flight on Phabricator editing! I mostly looked at other code, thought it was well written and wrote my own code in the other code's image.

Test Plan: Look at icons appearing!

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley

CC: Korvin, epriestley, aran

Differential Revision: https://secure.phabricator.com/D7911

src/view/phui/PHUIWorkpanelView.php

@@ -42,9 +42,15 @@ final class PHUIWorkpanelView extends AphrontView {
           $footer_tag);
     }
 
+    $header_edit = id(new PHUIIconView())
+      ->setSpriteSheet(PHUIIconView::SPRITE_ACTIONS)
+      ->setSpriteIcon('settings-grey')
+      ->setHref('#');
+
     $header = id(new PhabricatorActionHeaderView())
       ->setHeaderTitle($this->header)
-      ->setHeaderColor(PhabricatorActionHeaderView::HEADER_GREY);
+      ->setHeaderColor(PhabricatorActionHeaderView::HEADER_GREY)
+      ->addAction($header_edit);
 
     $body = phutil_tag(
       'div',