POC for Ansattporten integration

[danielskovli]

This PR exists only as a place to host the proof of concept, and is not intended for an actual merge.

The folder /AnsattportenPOC is self-contained and does not interact with the rest of the codebase in any way.

When launching, remember to have the following environment variables available:

Config__OidcClientId
Config__OidcClientSecret