Expand SAML-bridge with NextSession attribute

[DibranMulder]

In the SAML-bridge a SessionRequest is constructed according to the SAML Request done by Signicat. This SAML request now contains a list of requested attributes or a condiscon format. See https://developer.signicat.com/broker/signicat-identity-broker/authentication-providers/yivi.html#example-of-adding-condiscon-parameter-in-your-saml-request

The SAML request is translated to a SessionRequest here:
https://github.com/privacybydesign/irma-saml-bridge/blob/f84bd87727db58ff978f8f2f5970f970a43e2abd/src/main/java/nl/sidn/irma/saml_bridge/controller/RequestController.java#L395C9-L408

We should expand the SAML Request with an nextSession parameter. https://docs.yivi.app/chained-sessions#the-nextsession-url
This would allow Signicat clients to do ChainedSessions and issue an credential with for instance a pseudonym in it.