MDL-32824: Make dragdrop work correctly with section titles/links

MDL-32824: Make dragdrop work correctly with section titles/links

Initially, the default section title was swapped within the course format
javascript functions. Though some section titles may be custom and does not
require swapping, in addition they may have links to single section view. This
introduces some callback functions for define what needs to be done in
sections libs and js files.