DA - unions on content_tag and discussion_topic scopes

fixes CNVS-16816

test plan:
  - make sure that the following are properly filtered
    from modules with DA on/off
     - quizzes
     - assignments
     - graded discussions
     - ungraded discusisons
     - wiki pages
  - check for modules index & student progressions page
  - discussion topic index properly filters with DA
    ON and OFF

Change-Id: Id0e2e97d2d876dfb48968163bf140da42183a3c9
Reviewed-on: https://gerrit.instructure.com/45133
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Cody Cutrer <cody@instructure.com>
Reviewed-by: Cameron Sutter <csutter@instructure.com>
QA-Review: Sean Lewis <slewis@instructure.com>
Product-Review: Simon Williams <simon@instructure.com>