Assignment: Decouple bulk download folder names from 'alternativefullnameformat'

Currently, the assignment grading action "Download all submissions" creates folder names of the format "Firstname Surname_Somenumber_assignsubmission_file_", with Firstname/Surname/Somenumber filled in.

With a large number (>200) of participants, this is cumbersome, because everywhere else we sort them first by surname, then by first name.

Please (optionally) create folder names starting with "Surname Firstname" instead.