A teacher can provide example submissions in a workshop

1. Login as a teacher, add a workshop and tick the 'Use examples' checkbox.
2. Set the 'Mode of examples assessment' to 'Assessment of example submission is voluntary'.
3. Create the assessment form.
4. Add an example submission and create a reference assessment.
5. Switch the workshop to the submission phase.
6. Login as a student and assess the example submission.
7. Check that the reference assessment is displayed for comparison with the student's assessment.