OutputFilter.php uses broken classes from CMS

[Hackwar]

Steps to reproduce the issue

This is an issue that was found out in joomla/joomla-cms#38993 and is still valid in the current codebase of the filter package. In 0556634 the language class from the CMS is used in the OutputFilter class and besides that, the use-statement is wrong. So right now this stringUrlSafe() does not work.