feat(exporter): Add endpoint for RQ metrics

[tarunps]

Closes frappe/press#1283

• Adds endpoint to fetch RQ metrics for all benches on server
• Adds endpoint to fetch RQ metrics per bench
• Exempts all benches endpoint from token validation
  • Will be proxying this through nginx metrics endpoints and that has it's own validation setup
  • Force redirect the agent endpoint to nginx one

TODO:
- Add to nginx.conf

		location /agent/benches/metrics {
			return 301 /metrics/rq;
		}

		location /metrics/rq {
			proxy_pass http://127.0.0.1:25052/benches/metrics;
		}

[adityahase]

Looks good. Needs a few changes.

The exemption you added will make /agent/benches/metrics publicly accessible without credentials. Add a forced redirect in NGINX config to /metrics/rq.

Add "rq" in https://github.com/frappe/press/blob/26205eb65e9fd32234114299f17809424e63bfbf/press/api/monitoring.py#L55 So Prometheus scrapes this endpoint.

[ankush]

Looking at diff I can't quite figure out how will this work with bench workers... is this only intended for Agent RQ workers?