Add and update agent registration info to rig-server

[kaustavdm]

Agents need to tell rig-server:

• DNS of cluster they are part of
• Region they belong to
• Which infrastructure they are hosted on
• Total bandwidth they have
• Whether they are ready to receive traffic

[dolftax]

These metadata will be sent along with agent register request. But the health check / capacity of the nodes are done at stream load balancer logic. If node is full, traffic won't be routed. Will figure out more.

[kaustavdm]

Coming up here: https://github.com/applait/xplex-rig/blob/agent-api/rest/agent_handler.go

[dolftax]

Assign it back to me when done.