Cost Explorer API (1/n): Create a Helm chart for a dummy Python webserver for use as a local support chart dependency

[consideRatio]

For #4453, using a Cost Explorer API approach consider in #4648, create the Helm deployment part of the Python webserver needed as a backend for Grafana.

Definition of done

• A Helm chart defined under helm-charts/ is created and can be an opt-in dependency for the support chart config
• The Helm chart contains a Deployment, Service, and a ServiceAccount template (maybe something more?)
  • The ServiceAccount needs to have configurable annotations, and be declared to be used by the Deployment
• A Dockerfile is created having Python and a requirements file installed
• Chartpress can build the Dockerfile into an image and update values.yaml etc
• The helm chart is tested to deploy with a pod runnig a dummy Python application just printing Hello and sleeping or similar.