[5.2] use _JEXEC for restricted access#44193

pe7er merged 5 commits intojoomla:5.2-devjoomla/joomla-cms:5.2-devfrom

heelc29:4.4/jexec-usernameruleheelc29/joomla-cms:4.4/jexec-usernameruleCopy head branch name to clipboard