[WIP] Cloudjoule - support for Kubernetes

[PierreRustOrange]

This adds support for Kubernetes to smartwatts.

Main features

• Support for configuration through environment variables (partial support only, this should be bleanup up and moved to powerAPI instead of smartwatts)
• modifier agent, that monitors K8S and add K8S metatdata to reports (label, namespace, pod name, etc.)
• prometheus exporter with gauge and counter (should be preferred for such metrics with prometheus). This exporter exposes k8s metadata for all monitored pods.

This PR should be used as a basis for discussion, some code should most probably be moved to the PowerAPI repository and more care should be payed to make sure we don't cause any issue when running smartwatts outside k8s.