Modernize Phriction ordering/paging

Summary: Ref T7803. Fixes T7809. Move Phriction away from getReversePaging() / getPagingColumn().

Test Plan: Paged "All Documents", "Updated", and viewed document hierarchy.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: ite-klass, epriestley

Maniphest Tasks: T7809, T7803

Differential Revision: https://secure.phabricator.com/D12360

src/infrastructure/query/order/PhabricatorQueryOrderVector.php

@@ -92,6 +92,10 @@ final class PhabricatorQueryOrderVector
     return implode(', ', $scalars);
   }
 
+  public function containsKey($key) {
+    return isset($this->items[$key]);
+  }
+
 
 /* -(  Iterator Interface  )------------------------------------------------- */