Add examples for producing/consuming when ldap and oauth is enabled

[sebgott]

In the example ldap_to_oauth_plus_ldap a Confluent cluster with OAuth and LDAP is deployed. It would be nice if the example could also show an example of producing or consuming with external listeners for both of these options.

Scenario 1: I want to produce to Kafka with my keycloak client using OAuth.
Scenario 2: I want to produce to Kafka using my LDAP user.