sync file module items published state with file locked state

test plan:
* upload a file to a course and lock it
* add the file as a module item
* the item should be unpublished
* unlock the file
* the item should now be published (and visible
 to students)

fixes #CNVS-15206

Change-Id: Ifaaadf0117eeec44218c2fa8b4ca8c6957daa62d
Reviewed-on: https://gerrit.instructure.com/41996
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Jeremy Stanley <jeremy@instructure.com>
QA-Review: Jahnavi Yetukuri <jyetukuri@instructure.com>
Product-Review: Hilary Scharton <hilary@instructure.com>