Move PHUIFormBoxView to PHUIObjectBoxView

Summary: I'd like to reuse this for other content areas, renaming for now. This might be weird to keep setForm, but I can fix that later if we need.

Test Plan: reload a few forms in maniphest, projects, differential

Reviewers: epriestley, btrahan

Reviewed By: epriestley

CC: Korvin, aran

Differential Revision: https://secure.phabricator.com/D7120

src/applications/mailinglists/controller/PhabricatorMailingListsEditController.php

@@ -126,7 +126,7 @@ final class PhabricatorMailingListsEditController
           ->setName(pht('Create Mailing List')));
     }
 
-    $form_box = id(new PHUIFormBoxView())
+    $form_box = id(new PHUIObjectBoxView())
       ->setHeaderText($page_title)
       ->setFormError($error_view)
       ->setForm($form);