Allow a per user ordering of the courses in the myoverview dashboard

This is a fresh issue to discuss the need for this functionality and more accurately indicate the importance/need of this feature. The original issue being MDL-58203.

From the original(MDL-58203): 

A user should be able to change the ordering of the courses in the "sort-by-courses" view of the myoverview block by dragging them into a different order.

The ordering should be stored on a per user basis.

Initial discussion on MDL-58203