Identify builtin files and give them open policies

Summary:
Fixes T7379. Currently, builtin files generate with a "users" view policy even if an install is public.

Because these files TTL after 7 days, there's no migration here. Installs won't see the fix actually happen for up to 7 days after updating, though.

Test Plan:
  - Deleted a builtin.
  - Loaded projects page to regenerate it.
  - Saw new builtin had most open policy and was marked as a builtin.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T7379

Differential Revision: https://secure.phabricator.com/D11917

src/applications/files/controller/PhabricatorFileInfoController.php

@@ -222,6 +222,15 @@ final class PhabricatorFileInfoController extends PhabricatorFileController {
     $finfo->addProperty(pht('Viewable Image'), $image_string);
     $finfo->addProperty(pht('Cacheable'), $cache_string);
 
+    $builtin = $file->getBuiltinName();
+    if ($builtin === null) {
+      $builtin_string = pht('No');
+    } else {
+      $builtin_string = $builtin;
+    }
+
+    $finfo->addProperty(pht('Builtin'), $builtin_string);
+
     $storage_properties = new PHUIPropertyListView();
     $box->addPropertyList($storage_properties, pht('Storage'));