Add NATS Monitoring Dashboard for SigNoz

[kiran0113]

Summary

This PR introduces a complete NATS Monitoring Dashboard for SigNoz.
It includes metrics for NATS Core, JetStream, and the Prometheus exporter.

Features Included

• NATS server health (connections, routes, subscriptions, slow consumers)
• JetStream storage metrics (streams, consumers, bytes, messages)
• Stream and consumer lag visualization
• Top connections and subscriptions
• Process metrics (CPU, memory, GC)
• Exporter metrics (scrape errors, promhttp stats)

Use Case

This dashboard helps SRE and platform teams monitor the health and performance
of the NATS messaging system deployed on Kubernetes.

Additional Notes

• Designed to work with the NATS Prometheus Exporter on port 7777
• Compatible with SigNoz PromQL
• Can be extended with alert rules (available on request)

Please review and merge.

NOTE: Once the dashboard is imported, open every panel, select Edit, and then Save Changes.
This action refreshes the queries and all panels will display data.
Its working for me