Don't allow Guest users to move themselves into a paid seat
Problem to solve
Currently, a Guest user can move themselves into a paid seat by creating a project in their personal namespace and adding themselves to a role higher than Guest on that project.
This means that admins have less visibility and control over whether or not a user takes up a paid seat.
Guest users should either:
- Not be able to create personal projects
- Only have access to Free features on their personal projects