We want to add methods to the Cloud Storage client to support bidi streaming reads. It is unclear if these methods should live in a new client, or an existing client. It is clear that it will take multiple PRs to implement them, and potentially multiple breaking changes (to the new methods, the existing APIs should remain stable) as we write them. We should incubate these methods separate from google_cloud_storage::client::Storage until their API is stabilized and we are ready to release.

We will need to initialize a gaxi::grpc::Client, which means we need to have a ClientConfig.

We probably do not want to create a new ClientBuilder because maintaining it would be expensive.