Accommodate project reviewers in Differential search

Summary:
Ref T1279. Two changes to the search/query for Differential:

  - "Reviewers" now accepts users and projects.
  - "Responsible Users" now includes revisions where a project you are a member of is a reviewer.

Test Plan:
  - Searched for project reviewers.
  - Verified that the dashboard now shows reviews which I'm only part of via project membership.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T1279

Differential Revision: https://secure.phabricator.com/D7231

src/applications/search/engine/PhabricatorApplicationSearchEngine.php

@@ -254,11 +254,15 @@ abstract class PhabricatorApplicationSearchEngine {
    *
    * @param AphrontRequest  Request to read user PHIDs from.
    * @param string          Key to read in the request.
+   * @param list<const>     Other permitted PHID types.
    * @return list<phid>     List of user PHIDs.
    *
    * @task read
    */
-  protected function readUsersFromRequest(AphrontRequest $request, $key) {
+  protected function readUsersFromRequest(
+    AphrontRequest $request,
+    $key,
+    array $allow_types = array()) {
     $list = $request->getArr($key, null);
     if ($list === null) {
       $list = $request->getStrList($key);
@@ -266,9 +270,14 @@ abstract class PhabricatorApplicationSearchEngine {
 
     $phids = array();
     $names = array();
+    $allow_types = array_fuse($allow_types);
     $user_type = PhabricatorPHIDConstants::PHID_TYPE_USER;
     foreach ($list as $item) {
-      if (phid_get_type($item) == $user_type) {
+      $type = phid_get_type($item);
+      phlog($type);
+      if ($type == $user_type) {
+        $phids[] = $item;
+      } else if (isset($allow_types[$type])) {
         $phids[] = $item;
       } else {
         $names[] = $item;