Example configs for Beam on Flink kubernetes operator

[kennknowles]

The Flink project is working on an official Kubernetes operator. There have been several Flink Kubernetes operator implementations in the past, but having one tied to the Flink project is a good opportunity for Beam to offer a standard deployment solution.

We'd want to get wordcount to work in both Java and Python, and then publish the configs as a template users can modify for their own use cases. Similar to what we did for the GCP Flink operator: https://github.com/GoogleCloudPlatform/flink-on-k8s-operator/blob/master/docs/beam_guide.md

Imported from Jira BEAM-14210. Original Jira may contain additional context.
Reported by: ibzib.
Subtask of issue #19549