Implement the standard GRPC health checking protocol for remote tracker

[jiyuanq]

🚀 Feature

Implement the standard grpc health checkpoint protocol: https://github.com/grpc/grpc/blob/master/doc/health-checking.md

Motivation

Currently when we deploy remote tracker on k8s, there's no way to do meaningful readiness and liveness probe. The tcpSocket probe works but it's not a meaningful probe as mentioned here: https://kubernetes.io/blog/2018/10/01/health-checking-grpc-servers-on-kubernetes/ This health checking protocol will enable us to run readiness probe and liveness probe on k8s with "grpc-health-probe" tool: https://github.com/grpc-ecosystem/grpc-health-probe

Alternatives

An alternative is to expose an additional http endpoint for readiness and liveness probe on k8s