Connect connects to a PackageLoader gRPC server at 'addr', starting a server it if there isn't one, and restarting an existing one if it's out-of-date.

DeserializeProto deserializes a response from a PackageLoader gRPC service.

NewLoader creates a new Loader that sends RPCs on 'conn' with 'timeout'.

Loader calls a gRPC PkgLoader service to interpret BUILD files.