476 split environmental impact by k8s

[damienfernandes]

Closes #476

[demeringo]

Hi, thanks for the PR.

I did not look much in the code yet but a few quick remarks:

• we should provide a design doc (explaining the principle of scraping pods data already exposed in prometheus by a separate node exporter).
• we should also update user manual with and example of usage of the new paremeters.
• Maybe decorelate inventory of K8S resources from other cloud resources <(maybe a separate model).
• See if we can get rid of dependency against OpenSSL (For some libs I use rusttls as an alternative tls provider to ease cross compiliation: https://docs.rs/prometheus-http-query/latest/prometheus_http_query/#features
• fix the failing test
• make clippy happy by prefinging non used var by an underscore