Allow EditEngine configurations to be disabled and marked as "Default"

Summary:
Ref T9132.

Let configurations be enabled/disabled. This doesn't do much right now.

Let configurations be marked as default entries in the application "Create" menu. This makes them show up in the application in a dropdown, so you can replace the default form and/or provide several forms.

In Maniphest, we'll do this to provide a menu something like this:

  - New Bug Report
  - New Feature Request
  - ADVANCED TASK CREATION!!11~ (only available for Community members)

Test Plan: {F1005679}

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T9132

Differential Revision: https://secure.phabricator.com/D14584

src/applications/transactions/controller/PhabricatorEditEngineConfigurationListController.php

@@ -17,16 +17,16 @@ final class PhabricatorEditEngineConfigurationListController
   }
 
   protected function buildApplicationCrumbs() {
+    $viewer = $this->getViewer();
     $crumbs = parent::buildApplicationCrumbs();
 
-    $engine_key = $this->getEngineKey();
-    $edit_uri = "/transactions/editengine/{$engine_key}/edit/";
+    $target_key = $this->getEngineKey();
+    $target_engine = PhabricatorEditEngine::getByKey($viewer, $target_key);
 
-    $crumbs->addAction(
-      id(new PHUIListItemView())
-        ->setName(pht('New Form'))
-        ->setHref($edit_uri)
-        ->setIcon('fa-plus-square'));
+    id(new PhabricatorEditEngineConfigurationEditEngine())
+      ->setTargetEngine($target_engine)
+      ->setViewer($viewer)
+      ->addActionToCrumbs($crumbs);
 
     return $crumbs;
   }