Made it so public keys are stored in files with .pub extension

It is an attempt to solve issues with missing permissions on
pahabricator users.

scripts/gitadmin/rebuild_gitadmin.php

@@ -53,7 +53,7 @@ function handleSingleUserPHID(
         $key->getKeyType().' '.
         $key->getKeyBody().' '.
         $key->getKeyComment()."\n";
-      file_put_contents("$keydir/$member", $full_key_content);
+      file_put_contents("$keydir/$member.pub", $full_key_content);
     }
   }
   return $members;
@@ -121,7 +121,8 @@ function removeUnusedPublicKeys($keydir, $used_keys) {
   $files = scandir($keydir);
   foreach ($files as $file) {
     if (startswith($file, "PHAB")) {
-      if (!array_key_exists($file, $used_keys)) {
+      $member = basename($file, '.pub');
+      if (!array_key_exists($member, $used_keys)) {
         unlink("$keydir/$file");
       }
     }