Added: Cube Kubernetes deployment manifest

Resolves gitlab-org/gitlab#369026 (closed)

This is a development-only Kuberenetes deployment manifest for use with the GDK.

For production we will want to better understand how to tune this to weather high traffic.

Steps to test

• Test credentials
  • Host: clickhouse-server (this assumes you're running the clickhouse deployment
  • Database: default
  • Username: test
  • Password: test
• Set up the cluster
  • kubectl apply -Rf cube/manifests
• Expose ports
  • kubectl port-forward service/cube-service 4000:4000
• Test Cube out!
  • If you used the example queries from the Clickhouse deployment MR, you'll have 2M rows of data to play with.

TODO

• Steps to test
• Separate out into individual files