Add server-side tests for permission updates

[gjvoosten]

Technical debt description
#3532 changes how permissions are handled when privileged users are moved to a new position. Server-side (GraphQL client) tests should be added for the changed behaviour.

Proposed solution
Possible test cases include:

• remove person from admin position
• remove person from super user position
• remove person from normal user position
• remove person from principal position
• move person from admin position to admin position
• move person from admin position to super user position
• move person from admin position to normal user position
• move person from super user position to admin position
• move person from super user position to super user position
• move person from super user position to normal user position
• move person from normal user position to admin position
• move person from normal user position to super user position
• move person from normal user position to normal user position
• move person from principal position to principal position
• set admin position to inactive
• set super user position to inactive
• set normal user position to inactive
• set principal position to inactive
• set person holding an admin position to inactive
• set person holding a super user position to inactive
• set person holding a normal user position to inactive
• set person holding a principal position to inactive