This moves the generated pb files to the `sdk` module. This allows third parties to make use of them if desired (e.g. in upcoming plugins) and moves away from the `gen` nomenclature in the directory, since we are going to be adding some extra interface functions to the messages.
* Possible api changes.
* Worker API update.
* Updating import alias name.
* Moving session down a level as a member of the GetSessionResponse.
* Marshal the auth flag into the GetSessionResponse proto instead of the session.