Reviewers should be able to assign Exercise-Groups to Tutors

Description / Overview

Reviewers should be able to assign and edit exercise-groups for tutors, as this is not possible yet when tutors register via the instance password.

Use cases

In exercise-mode tutors should (only) have access to the participants of their exercise-group etc. That only works if tutors are assigned to their exercise-groups as well.

Links / references

Feature checklist

• Add drop-down to the tutor-list-page where reviewers can assign groups for each tutor.
• Undo latest changes to the participants-page so tutors can only see participants of their groups.