metrics: allow configuring IP address & port for exposing metrics in iroh-relay

[missytake]

Right now, iroh-relay exposes metrics to 127.0.0.1:9092.

To scrape metrics from iroh-relay hosts via wireguard, we need to expose the port to the wireguard network, other wireguard hosts can't see the metrics otherwise.

Maybe this could be added to the iroh-relay command via a --metrics 192.168.0.10:9093 command line flag?

[Arqu]

Glad people are running their own these days :)
The relay already has a configuration mechanic, see this.
The intent was to keep the CLI simple to reduce the surface area and provide a way for a quick way to run it.
In general if you're running it as a service you would probably want to supply a full config file with everything fleshed out. That would also include the metrics_bind_addr.