show module names on draft state assignment index

fixes CNVS-12216

test plan
- as a teacher
- in a course with 11+ modules
- with 1+ assignment in each module
- visit the assignment index page
- all module names should be listed (instead of 'Module')

Change-Id: I57b5f1219105e21db6fe48407422fc9385773bdf
Reviewed-on: https://gerrit.instructure.com/34083
Tested-by: Jenkins <jenkins@instructure.com>
QA-Review: Anna Koalenz <akoalenz@instructure.com>
Reviewed-by: Cameron Sutter <csutter@instructure.com>
Product-Review: Liz Abinante <labinante@instructure.com>