Issue #3449491: ResponsiveMenus sometimes adds multiple click handlers to the toggle and accordion controls breaking them

This makes changes to at_core/scripts/at.responsiveMenu.js but does not make corresponding changes to at_core/scripts/min/at.responsiveMenu.min.js. In order to ensure it works, I also changed at_core/at_core.libraries.yml to use the main file instead of the minified file.