Improved metrics + default dashboard

[janekbaraniewski]

Dummy metrics are in place, once everything is working they should be improved to provide some actual data.

It would also be cool to include some default dashboard in chart

[janekbaraniewski]

Scope note: besides the dummy gauges (registered but never .Set()), there's a latent bug — InjectedCommands in pkg/webhooks/metrics.go is .Inc()'d but never added to MustRegister, so it is never scraped. The fix for this issue should (1) populate the gauges from reconciler/monitor state, (2) register InjectedCommands, and (3) ship a Grafana dashboard ConfigMap in the chart.