Client helpers for generated protobuf library

[lucasoares]

Now that #29 allow users assign the priority score manually, we should create helpers in our native-supported gRPC libraries (that we compile and provide to be used in a package registry) to help users manage these scores.

Utility examples:

• Method to create score using the default algorithm
• Method to get a score from a given time (in its native type for each language)
• Constants for score (Min, Max and Undefined)