Create alerts & runbooks covering major Coder architectural components, deployment environment

[dannykopping]

• Failure to connect to database
• No coderd replicas up
• No provisioner replicas up
• Pod OOMs (special handling for workspaces?)
• Resource usage exceeding margin
  • CPU
  • Memory
  • Disk (requires metrics-server to be installed)
  • License seats
• Workspace build failures
• Pod restarts
• Workspace proxy failures (coderd_proxyhealth_health_check_results)
  • add proxy name as label
  • add error code as label, use to link to documentation