Add grpc root service for test configuration

When facade_main and cert_main is started, it only starts grpc root
service, and listens for StartStack() request before brining up required
modules. Then, it listens for StopStack() request before cleaning up
modules. Defining new rootservice.proto for facade and cert.

Test: cert/run_cert.sh
Change-Id: I10fa745b9a235080be7a0c82fe7f3a297c1a112d