fix: send authentication reject on missing res* in authentication response

[gruyaume]

Description

Send an authentication error instead of error indication whenever Ella Core receives an authentication response missing RES*.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have made corresponding changes to the documentation
• I have added tests that validate the behaviour of the software
• I validated that new and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules