Resolve "Warn user if edition path has no group on gitlab"

Summary

Reformatted the warning to show links and use messages.

Checklist

All items on this checklist should be checked.

• I have added a changelog entry.
• I have added tests for the functionality that I added.
• I adhere to the style guide.

How to review

Setup an edition, try out different path types to see the error messages. You can have a path that does not exist, (including a course without edition), a project, and a group.

Screenshots

Issues and tasks closed

Closes #90