Show hidden editions to head-TAs

Description

Head-TAs now cannot see the edition in Submit and thus not configure it unless it is made visible to all students

Checklist

• Head-TA should be able to see the hidden courses they head-TA for in the overview
• The hidden status should be added as a badge to the overview

Reasoning

The course should be configured before making it visible and its hidden status should be clear for those that can see that edition.