Use same credentials for MAC based protection: Adapt configuration interface

[Akretsch]

Issue Report

Followup to #91

Expected Behavior

It shall not be possible to configure responding shared secret protection.

Current Behavior

Currently the downstream configuration allows to configure independent outgoing password based protection. But this configuration is ignored.

Possible Solution

Change the interface classes accordingly. This fix will break interface compatibility.

Steps to Reproduce

Use shared secret protection on downstream and configure outgoing shared secret protection on downstream.

Possible Implementation

Refactor classes around https://github.com/siemens/cmp-ra-component/blob/main/src/main/java/com/siemens/pki/cmpracomponent/configuration/CredentialContext.java