Proxy status Rest/gRPC endpoint

### What should we add or change to make your life better?
Provide a Rest or gRPC endpoint for querying the proxy status and configuration
### Why is this important to you?
When multiple instances of the proxy are deployed, you'll want to be able to centrally manage the configuration and understand the status.

Builds upon #125 (API for proxy status), and is a foundation for #123 Proxy Dashboard.

Tracking these as a set of related work items as they build upon each other and can be delivered independently.