false if a UserGetRights hook might remove the named right.
$right: The user right being checked
-'UserIsHidden': Check if the user's name should be hidden. See User::isHidden().
+'UserIsHidden': DEPRECATED since 1.34 - use GetUserBlock instead, and add a
+system block that hides the user. Check if the user's name should be hidden.
+See User::isHidden().
$user: User in question.
&$hidden: Set true if the user's name should be hidden.