Kerberos support for Beats

[kvch]

In #15619 we decided to use github.com/jcmturner/gokrb5 to support Kerberos in Beats. The goal of this effort is to add support for the following:

• Kerberos authentication for Elasticsearch Kerberos Authentication for Elasticsearch #7404
  • Elasticsearch output
  • Add end to end tests Add Kerberos-aware Elasticsearch and integration test to ES output #18127
  • Update documentation of ES output
• Kerberos authentication for Kafka Kerberos Authentication for Kafka #5413
  • Kafka input Add Kerberos support to Kafka input and output #16871
  • Kafka output Add Kerberos support to Kafka input and output #16871
  • Add end to end tests Add Kerberos-aware Kafka to testing env #16904
  • Update documentation of Kafka output
  • Update documentation of Kafka input

[fbaligand]

Great new feature!
I'm very interested, especially for Kafka authentication!

[jlind23]

Closing it in favour of #5413 which is the only task left.