feature: Add Grafana dashboard

[nunoadrego]

Checklist:

• I've searched for similar issues and couldn't find anything matching
• I've discussed this feature in the #k8sgpt slack channel

Is this feature request related to a problem?

• Yes
• No

Describe the solution you'd like

After the merge of #273, there is an opportunity to create a Grafana dashboard to display the metrics.

While discussing this idea on Slack, it was suggested that we use a ServiceMonitor from Prometheus operator. We can also explore the possibility of having the Grafana operator in the cluster for the full-fledged solution.

Finally, the dashboard can be stored in this Github repo as plain json as well as submitted at the Grafana community dashboards page.

Benefits for the project and its users

We will get a visual representation of the exported metrics, namely the errors per analyzer.

Potential drawbacks

Additional context

[nunoadrego]

Can you assign this to me? Thanks in advance.