As a teacher
I want to be able to hide and show sections and see the change applied in the course index
so I don't need to reload the page to confirm the changes were properly applied.
- Hidden section is styled differently in the course index
- Section visibility is synchronized between Course index and course main content area.
- When a section is shown in the course main content area is also marked as visible in the course index.
- When a section is hidden in the course main content area is also marked as hidden in the course index.