Create option to extract Issuer DN from PKI

Feature Request

Why

DAF CLOUDworks has a customer requesting the JWT issued by Keycloak include the issuer DN.

Proposed Solution

In addition to the options here, can we add an Issuer DN option, that allows us to create an attribute that contains the Issuer DN, and then pass that in the JWT.

If we can make the attribute, our setup can then pass it in the identity token.