DA - modules

fixes CNVS-14095
fixes CNVS-15157

test plan:
  - with DA on and off
    - go to modules page
      - only the right assignments show
      - completion requirements ignore
        assignments that cant be seen by a user
    - modules page works with changing sections
      - complete/incomplete updates properly
      - as does locked/unlocked
    - modules page shows correct content when
      a students grade is deleted and this makes
      them lose assignment visibility
    - modules api doesnt return any content that
      a student cannot see

Change-Id: Ia1acfd919214823cdfc3b45e974876b4529bb14d
Reviewed-on: https://gerrit.instructure.com/38970
Product-Review: Hilary Scharton <hilary@instructure.com>
Reviewed-by: Simon Williams <simon@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>
QA-Review: Mike Nomitch <mnomitch@instructure.com>