Fix tests

[SpeedyCoder]

• Fix the broken NATS streaming test
• Move the generated proto files to publicly accessible package so that they can be used in substrate.
• Change generated file in proximoc, so that its exported types and functions just point to the ones generated for the server. This fixes the tests as we don't get panic: proto: duplicate enum registered: proximo.Offset anymore. This doesn't break the API of the client library, so everything using it should be fine. Other way around this would be to implement a client just for testing the server, but that seems like way to much unnecessary work

[mjgarton]

"Move the generated proto files to publicly accessible package so that they can be used in substrate."

Why?

This creates a dependency from substrate on proximo just to save a line or two of protoc command.

"A little copying is better than a little dependency."