Adding a subchart to include prometheus as a data source for grafana

[felipemontoya]

Prometheus is necessary to add in the cluster even if it already has metric-server because it can provide more detailed and comprehensive metrics than metric-server. Prometheus can also offer more flexibility and functionality than metric-server, such as custom queries, labels, and histograms. It also connects to grafana to enhance the dashboard capabilities.

For context, we have discussed in #26 that monitoring is still required to get this project to production ready mode.

Following the installation of metrics server in #17 issue #3 was split into this issue specific for prometheus and #37 for grafana.