Add the list of labels associated with metrics Used and Unused in rules and dashboards

[sswieton]

Is your feature request related to a problem? Please describe.

An interesting feature for helping in cardinality optimization would be to have, for each metric, the list of labels present in the regular expressions. This would provide significant assistance in identifying high cardinality labels.

Describe the solution you'd like

in the reports, metrics-in-grafana.json and metrics-in-rules.json, we currently have the list of metrics used per dashboard. Additionally, we could include the list of labels associated with these metrics.

thanks