Conpherence - get the durable column header actions working correctly

Summary:
Ref T7014. This diff addresses

 - getting it to be the right set of options
   - add participant
   - view in conpherence
   - close window
 - making those options work
 - make it so if you are on /conpherence/ you can't toggle the durable column

Test Plan: inspected dom via chrome tools and found last transaction. added a participant and inspected the single new transactin added for accuracy. used view in conpherence action to view in conpherence. used close window action to close window

Reviewers: chad, epriestley

Reviewed By: epriestley

Subscribers: Korvin, epriestley

Maniphest Tasks: T7014

Differential Revision: https://secure.phabricator.com/D11991

src/applications/conpherence/controller/ConpherenceUpdateController.php

@@ -209,14 +209,19 @@ final class ConpherenceUpdateController
         ->setDatasource(new PhabricatorPeopleDatasource()));
 
     require_celerity_resource('conpherence-update-css');
-    return id(new AphrontDialogView())
+    $view = id(new AphrontDialogView())
       ->setTitle(pht('Add Participants'))
       ->addHiddenInput('action', 'add_person')
       ->addHiddenInput(
         'latest_transaction_id',
         $request->getInt('latest_transaction_id'))
       ->appendChild($form);
+
+    if ($request->getExists('minimal_display')) {
+      $view->addHiddenInput('minimal_display', true);
     }
+    return $view;
+  }
 
   private function renderRemovePersonDialogue(
     ConpherenceThread $conpherence) {