feat: configure grafana and prometheus

[brendontan03]

Summary

This PR adds the configurations required to run grafana and prometheus on devnet.

Details

• Add metrics flag to enable metrics monitoring on RPC and sequencer nodes
• Add script to automatically generate prometheus.yml file
  • cd to devnet/monitoring
  • Make a copy of example.env to .env
  • In the .env file, fill in the IP addresses of sequencer and RPC nodes under the respective sections
  • Run ./generate_prometheus_config.sh to generate prometheus.yml file
• To view grafana dashboard
  • Run make run to start local devnet
  • Go to localhost:3000 on the browser
  • Default username and password are both admin
  • Select Dashboards from sidebar and choose XLayer Monitoring