Modernize "user, project or package" typeahead datasource

Summary: Ref T4420. Call this "auditor" since that's what it is.

Test Plan:
  - Edited auditors in auditor search.
  - Edited auditors in "add auditors" in Diffusion.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T4420

Differential Revision: https://secure.phabricator.com/D9888

src/applications/audit/query/PhabricatorCommitSearchEngine.php

@@ -85,7 +85,7 @@ final class PhabricatorCommitSearchEngine
     $form
       ->appendChild(
         id(new AphrontFormTokenizerControl())
-          ->setDatasource('/typeahead/common/usersprojectsorpackages/')
+          ->setDatasource(new DiffusionAuditorDatasource())
           ->setName('auditorPHIDs')
           ->setLabel(pht('Auditors'))
           ->setValue(array_select_keys($handles, $auditor_phids)))