spec: add tests for assignment student visibility
spec: add tests for assignment student visibility

refs CNVS-38346

test plan:
* ensure Jenkins passes

Change-Id: I9e81822a5711f4055755d7f50b0ac925a7161760
Reviewed-on: https://gerrit.instructure.com/120917
Tested-by: Jenkins
Reviewed-by: Spencer Olson <7cc0890d6f1f70810a023e7173eca5724d6c8e49@instructure.com>
Product-Review: Jeremy Neander <20252aad5efdc666f083d82ab63ed0f9f72a043e@instructure.com>
QA-Review: Jeremy Neander <20252aad5efdc666f083d82ab63ed0f9f72a043e@instructure.com>

djbender/canvas-lms,djbender/canvas-lms,venturehive/canvas-lms,instructure/canvas-lms,sfu/canvas-lms,venturehive/canvas-lms,instructure/canvas-lms,sfu/canvas-lms,instructure/canvas-lms,instructure/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,instructure/canvas-lms,djbender/canvas-lms,sfu/canvas-lms,instructure/canvas-lms,djbender/canvas-lms,sfu/canvas-lms,venturehive/canvas-lms,venturehive/canvas-lms,instructure/canvas-lms,sfu/canvas-lms