Use configuration key in user log messages for all Issuer modules

We display some logs when a user is allowed to access a CAS/SAML/OIDC application, but we don't use the same attribute to identify the application:

• With CAS: the service URL
• With SAML: the SP entityID
• With OIDC: the RP configuration key

I think it would be better to use the configuration key, whatever the protocol is. It could have an impact for people parsing log messages, but I would like to add this in %2.0.9 with an upgrade note.

We should also add a log in Issuer get code.