fix(exitError): Move cleanhtmljs() into `Lib.Util.php` and add missing include_once (refs #4838)

Move definition of cleanhtmljs() into `Lib.Util.php` and add missing
include_once("FDL/Lib.Util.php") in `Class.Action.php`.
Merge pull request #1232 from eguaj/3.2-A4838

fix(exitError): Move cleanhtmljs() into `Lib.Util.php` and add missing include_once (fixes #4838)