Convert PhD student to Supervisor

1. Firstly, create an additional external person: in the Persons tab, click the New button in the bottom left. Complete the fields as much as possible and click Save.
2. Link this external person to the old PhD trajectory as a PhD student (this overwrites the old, internal PhD student)
3. In users, change that external person to the role of supervisor.
4. Mail the supervisor and report that the completed PhD trajectory is now linked to an e-number; and that the supervisor role is now linked to the p-number. This should solve the problem and the supervisor should be able to access the trajectories linked to her/him.

See Trello RUG1936. Incidentally, as soon as someone is added as (co-)supervisor to a PhD trajectory, this person then automatically gets a promoter role; and he/she can then see the trajectories of his/her PhD students.