Manage SCRAM users in an authenticated broker

[rmarting]

This PR completes the #10 with the tasks to operate (create, describe, and delete) SCRAM users in a Kafka cluster with authentication enabled.

Update the Authentication test case

[rmarting]

@rpelisse PR to complete the #10 ready for your review. CI :green_circle: :smile:

[Neustradamus]

@rmarting: Good job as always!

Linked to:

• https://github.com/scram-sasl/info/issues/1