Add a default "Subscribed" query to Maniphest

Summary: Although I don't want to end up with 20 of these again, this is a reasonable default to provide, particularly for installs where a large portion of the userbase primarily reports bugs and does not interact with them directly.

Test Plan: Hit `/maniphest/`, saw "Subscribed", clicked it, saw the tasks I'm subscribed to.

Reviewers: jbrown, btrahan

Reviewed By: jbrown

CC: aran

Maniphest Tasks: T4100

Differential Revision: https://secure.phabricator.com/D7586

src/applications/maniphest/query/ManiphestTaskSearchEngine.php

@@ -362,6 +362,7 @@ final class ManiphestTaskSearchEngine
     if ($this->requireViewer()->isLoggedIn()) {
       $names['assigned'] = pht('Assigned');
       $names['authored'] = pht('Authored');
+      $names['subscribed'] = pht('Subscribed');
     }
 
     $names['open'] = pht('Open Tasks');
@@ -384,6 +385,10 @@ final class ManiphestTaskSearchEngine
         return $query
           ->setParameter('assignedPHIDs', array($viewer_phid))
           ->setParameter('statuses', array(ManiphestTaskStatus::STATUS_OPEN));
+      case 'subscribed':
+        return $query
+          ->setParameter('subscriberPHIDs', array($viewer_phid))
+          ->setParameter('statuses', array(ManiphestTaskStatus::STATUS_OPEN));
       case 'open':
         return $query
           ->setParameter('statuses', array(ManiphestTaskStatus::STATUS_OPEN));