Person entity can not be added to a Project

[EikLoe]

Describe the bug When creating a new project via the submission workflow, you can't connect a corresponding person entity. If you select the wanted person, you get an error alert: No suitable match could be found for relationship type isProjectOfPerson between the two items

To Reproduce

1. Login on DSpace and open the submission form for a new Project-Entity (via MyDSpace)
2. Search for an Investigator via the relationship-lookup.
3. Select a person entity --> You get an alert and not relationship is created

Expected behavior I expect a relationship to be created and the corresponding metadata to be displayed.

Related work

I could try to provide a PR to fix this.