Create a structured output format for cardamon stats (json/yaml)

[flyaruu]

We're running cardamon in a CI environment. The CI run results in a cardamon.db sqlite database, which can be analyzed, but I'd like an easier way to for example detect energy usage regressions.

I think the easiest way to get there is to extend the 'cardamon stats' command with a JSON output option '-o json' so we can parse it with jq, and for example fail a build if the energy consumption is much higher.