Use PHUIListItemView in ConpherenceThreadList

Summary: Fixes T12556 Uses more common components in ConpherenceThreadList by moving to PHUIListItemView. Reduces clutter by moving privacy into the header. Gets ride of "See More" double interchanges.

Test Plan:
I need to test this more, doesn't seem to auto-select top room any more, also might build a lipsum generator.

 - Create lots of rooms with various policies
 - Test clicking on policy object
 - Click on different rooms
 - Post in rooms
 - Load up second account, see room numbers
 - Clear room message count by clicking on room

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Maniphest Tasks: T12556

Differential Revision: https://secure.phabricator.com/D17698

src/applications/conpherence/controller/ConpherenceUpdateController.php

@@ -522,18 +522,12 @@ final class ConpherenceUpdateController
     $people_widget = null;
     switch ($action) {
       case ConpherenceUpdateActions::METADATA:
-        $policy_objects = id(new PhabricatorPolicyQuery())
-          ->setViewer($user)
-          ->setObject($conpherence)
-          ->execute();
-        $header = $this->buildHeaderPaneContent(
-          $conpherence,
-          $policy_objects);
+        $header = $this->buildHeaderPaneContent($conpherence);
         $header = hsprintf('%s', $header);
         $nav_item = id(new ConpherenceThreadListView())
           ->setUser($user)
           ->setBaseURI($this->getApplicationURI())
-          ->renderSingleThread($conpherence, $policy_objects);
+          ->renderThreadItem($conpherence);
         $nav_item = hsprintf('%s', $nav_item);
         break;
       case ConpherenceUpdateActions::ADD_PERSON: