Protobuf benchmarks

[dmathieu]

We do have some Go benchmarks, but as we're trying to optimize our protobuf setup, it would be nice to have an automated/reproducible way of benchmarking our protobuf setup as well.

So the idea here is to setup a suite of benchmarks which would setup structs from the generated protobuf definitions, and analyze the generated size of the objects, and time to encode/decode.