[ticket/12722] Add Generic.Formatting.SpaceAfterCast in the legacy ruleset

https://tracker.phpbb.com/browse/PHPBB3-12722

I think that it's a good idea to have this rule, but also it's nice to be able to format the assignments like in phpBB/includes/acp/acp_jabber.php

PHPBB3-12722
Also remove the space at the fron here, please.