Fix an exception with user cache generation in "bin/conduit call --as <user>"

Summary:
Ref T13249. Using "--as" to call some Conduit methods as a user can currently fatal when trying to access settings/preferences.

Allow inline regeneration of user caches.

Test Plan: Called `project.edit` to add a member. Before: constructing a policy field tried to access the user's preferences and failed. After: Smooth sailing.

Reviewers: amckinley

Reviewed By: amckinley

Maniphest Tasks: T13249

Differential Revision: https://secure.phabricator.com/D20255

src/applications/conduit/management/PhabricatorConduitCallManagementWorkflow.php

@@ -58,6 +58,10 @@ final class PhabricatorConduitCallManagementWorkflow
             'No such user "%s" exists.',
             $as));
       }
+
+      // Allow inline generation of user caches for the user we're acting
+      // as, since some calls may read user preferences.
+      $actor->setAllowInlineCacheGeneration(true);
     } else {
       $actor = $viewer;
     }