[Enhancement] Support Kerberos based authentication type

[donovanmuller]

Is your feature request related to a problem? Please describe.
Support for configuring Kerberos authentication for Mirror Maker consuming/producing from external brokers with Kerberos based authentication.

We use a security configuration similar to the following to use Kerberos based authentication to the brokers:

Example strimzi-producer.properties

bootstrap.servers=...
sasl.mechanism=GSSAPI
security.protocol=SASL_PLAINTEXT
sasl.kerberos.service.name=kafka
sasl.jaas.config=com.sun.security.auth.module.Krb5LoginModule required \
  useKeyTab=true \
  storeKey=true \
  keyTab="xxx.keytab" \
  principal="test@test.com";

the above configuration is not possible today, given that sasl. is a forbidden property.
The above is in context of using Mirror Maker, when producing to external brokers.

Describe the solution you'd like
The ability to describe the configuration above would prevent us from having to build a custom image and using a stand alone deployment (not via KafkaMirrorMaker CR) of Mirror Maker to be able to configure the above.

Describe alternatives you've considered
We currently build a custom image the and run as a stand alone Deployment.

[scholzj]

I think this is more or less duplicate to #3088

[scholzj]

Closing as duplicate to #3088