Fix breadcrumbs for login screen triggered when a logged-out user fails a policy check

Summary:
Ref T603. Currently, if you're logged out and try to view some object which requires you to be logged in, the login screen is missing the application breadcrumb and just says "Login".

Add the application in context so we get the keys icon.

Test Plan: {F69255}

Reviewers: chad, btrahan, asherkin

Reviewed By: chad

CC: aran

Maniphest Tasks: T603

Differential Revision: https://secure.phabricator.com/D7303

src/aphront/configuration/AphrontDefaultApplicationConfiguration.php

@@ -161,6 +161,11 @@ class AphrontDefaultApplicationConfiguration
         // Possibly we should add a header here like "you need to login to see
         // the thing you are trying to look at".
         $login_controller = new PhabricatorAuthStartController($request);
+
+        $auth_app_class = 'PhabricatorApplicationAuth';
+        $auth_app = PhabricatorApplication::getByClass($auth_app_class);
+        $login_controller->setCurrentApplication($auth_app);
+
         return $login_controller->processRequest();
       }