A pundit transformer instance should not be hard linked to a platform instanc

[retog]

Rather than being connected to a platform instance vie environment variables it should have the URI of the platform as a parameter to the transformer URIs.

Somehow related: On https://github.com/fusepoolP3/p3-platform-reference-implementation/blob/master/marmotta/docker-compose.yml#L57 I don't understand how the service determines the URI of the User Interaction registry from the provided parameters and why 3 links are needed.