2.4 compat - fixes and enhancements for courses in Awesomebar

Removes unnecessary "Current course" node, replacing it with the child directly.  Also brings back the missing list of courses under "My courses".
Awesomebar improvements and fixes

Including:
* Removal of legacy onclick handlers - this stops JS errors when the Navigation block is not present
* Promotion of the course node under "current course" to direct child of nav menu (removal of "current course" node in between)
* Fix categories in My Courses branch (if enabled)