[Security] Support new sap_id_typeclaim

[CharlesDuboisSAP]

Context

• SAP/cloud-sdk-java-backlog#502.
• Adopt to sap_id_type to solve principle resolution #1096

New for SCI is now a sap_id_type claim. This claim is always in the JWT (id and access token).
With value app you can rely on a client authentication only and the sub is then always the client_id.

With value user you can rely on a User authentication and then you can rely that sub is the user identifier. This Identifier is called Subject Name Identifier in SCI and in the Admin UI customers can define this. Typically the userId, or email or user_uuid.

Feature scope:

• Support new sap_id_type claim

Definition of Done

• Functionality scope stated & covered
• Tests cover the scope above
• Error handling created / updated & covered by the tests above
• Documentation updated
• Release notes updated

[strehle]

@torsten-sap FYI