A teacher can choose whether hidden course sections are shown collapsed

1. Login as a teacher, access a course then in the settings, set the hidden sections to be shown as collapsed.
2. Hide a couple of sections on the course page by clicking the hide/show eye icon.
3. Login as a student, access the course and check that the hidden sections are displayed in collapsed form with no content.
4. Login as the teacher again, access the course settings and set the hidden sections to be completely invisible.
5. Login as the student again, access the course and check that the hidden sections are not displayed at all.