Add prometheus r-proxy

[derfredy]

Hi, thanks for this fantastic code! It really makes our daily tasks more confortable.

I would add a new r-proxy with almost the same tasks for prometheus 9615 daemon port.

• New task in firewall.yml
• New var for prometheus public port
• New nginx server block on proxy.conf.j2 template

I am not sure if this should also use the auth basic method or if we could allow a "From IP" at firewall level.

[fgimenez]

Thanks a lot @derfredy!! <3

We plan to include the ability to take into account bastion IPs shortly, for now we can start by leveraging the existing basic auth used in node-exporter endpoint. Will ping you in the PR :)