make quiz assignment creation appear in main stream items in the dashboard

fixes CNVS-11209

test plan:
  - turn on draft state
  - create and publish a quiz
  - go to the main dashboard and courses dashboard
  - the quiz that was created shoulda ppear on the mains stream items list

Change-Id: Iadc3f41f2baa6b35114e267fbea6fd4e5e7feff6
Reviewed-on: https://gerrit.instructure.com/33805
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Josh Simpson <jsimpson@instructure.com>
QA-Review: Caleb Guanzon <cguanzon@instructure.com>
Product-Review: Derek DeVries <ddevries@instructure.com>