fix(build): Allow creating multiple services in the same package (#173)

BREAKING CHANGE: Build will now generate each service client and server into their own modules.

tonic-examples/src/tls/client.rs

@@ -2,7 +2,7 @@ pub mod pb {
     tonic::include_proto!("/grpc.examples.echo");
 }
 
-use pb::{client::EchoClient, EchoRequest};
+use pb::{echo_client::EchoClient, EchoRequest};
 use tonic::transport::{Certificate, Channel, ClientTlsConfig};
 
 #[tokio::main]