ignore unpublished module items for course progress

fixes CAT-79

test plan:
1. Enable Draftstate on a course that has gallery set up
2. Set up a module with multiple module items
3. unpublish some of the module items ( individually)
* verify that the "requirement_count" adjusts to the
* unpublishing of items for the following endpoint:

/courses/:course_id?include[]=course_progress

Change-Id: I092b8c7a76a1abf4b05bd0a0ed654bee98de0217
Reviewed-on: https://gerrit.instructure.com/35654
Reviewed-by: Jeff Belser <jbelser@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>
Product-Review: Marc LeGendre <marc@instructure.com>
QA-Review: Marc LeGendre <marc@instructure.com>