Update HTTP Proxy dashboards to show when downstream proxy resources are unhealthy

[scotwells]

Summary

The HTTP Proxy dashboard only shows the status of the HTTP Proxy resource. It does not show the health / status of downstream resources like Gateways, HTTPRoutes, etc that are required to make an HTTP Proxy work correctly.

Acceptance Criteria

• Proxy dashboard has new state timeline panels indicating health of downstream http proxy resources
• Nice to have: Commit dashboard code as grafonnet.