allow unpublished module items to be reordered

test plan:
 - have a course with draft state enabled
 - have a bunch of unpublished module items
 - reorder them
 - reload the page and make sure the order sticks

fixes CNVS-10906

Change-Id: I47713b454cce41330803eb742455697b4a26e0b0
Reviewed-on: https://gerrit.instructure.com/29591
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Bracken Mosbacker <bracken@instructure.com>
Product-Review: Bracken Mosbacker <bracken@instructure.com>
QA-Review: Nathan Rogowski <nathan@instructure.com>