Implement health check for gRPC server implementation.

[Tsuyoshi Ushio]

Current version doesn't have liveness/readinesProbe on the yaml/helm chart since the image is for gRPC server not http server.

However, we can do it with this idea.
https://kubernetes.io/blog/2018/10/01/health-checking-grpc-servers-on-kubernetes/
We can use grpc-health-probe binary.

Success Criteria

• helm chart is updated to implement health checking liveness/readinessProbe
• deployment is fully tested as automated testing

Dependency

• #2
• #12