Reduce mongo calls on course outline and container pages

STUD-2076. @cahrens @dan-f @dmitchell please review.
You need to change the 2nd usage of _course_outline_json to pass in the course_module instead of the couse_key. I blieve that is the cause of the failing unit tests.

```python
return JsonResponse(_course_outline_json(request, CourseKey.from_string(course_key_string)))
```