* Protobuf changes
* Move management of root resource state to engine
This commit fixes a persistent side-by-side issue in the NodeJS SDK by
moving the management of root resource state to the engine. Doing so
adds two new endpoints to the Engine gRPC service: 1) GetRootResource
and 2) SetRootResource, which get and set the root resource
respectively.
* Rebase against master, regenerate proto