Run tangle + prometheus in k3d for metrics/dashboard testing

**Is your feature request related to a problem? Please describe.**
- Not a huge way of testing Helm deployments!
- No out-of-box dashboards!

**Describe the solution you'd like**
- [Example](https://dev-devops.com/blog/devops/k3d-prometheus-grafana#install-kube-prometheus-stack) of installing the promstack.
- Dogfood own Helm charts.