A teacher can set repeated chat times

1. Log in as a teacher, update a chat activity and set repeat sessions at the same time every day.
2. Go to the calendar and update the "All courses" dropdown to select the name of the course.
3. Check that next scheduled chat session appears in the calendar.
4. Update a chat activity and set repeat sessions at the same time every week.
5. Go to the calendar and update the "All courses" dropdown to select the name of the course.
6. Check that next scheduled chat session appears in the calendar.

Note: Only the next scheduled chat session should appear in the course calendar and not every session.