Cost Explorer API (8/n): allow aws-ce-grafana-backend software to be traitlets configurable (in a "chart passthrough" manner)

[consideRatio]

Its not clearly decided what should be configured and how, but we need a system to provide configuration for the software.

An example of something that needs to be configurable is the clustername (the AWS resource naming, so openscapeshub and not openscapes for example).

Definition of done

• Establish a traitlets based system that allows chart config -> software config in a way that doesn't make the chart understand what software config can be used.
  Z2JH does this via jupyterhub.hub.config for example.
• Setup the software to work with traitlets based config, trial with cluster_name
• Setup and verify passthrough chart config of cluster_name works

[consideRatio]

I'm dropping this and going for hardcoded things as setting up a traitlets based system to configure the application was something I struggled with.

[consideRatio]

I've ended up settling for introducing a chart configurable environment variable for the cluster name, and will not try to make anything else configurable.