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.

tests/included_service/src/lib.rs

@@ -5,4 +5,4 @@ pub mod pb {
 // Ensure that an RPC service, defined before including a file that defines
 // another service in a different protocol buffer package, is not incorrectly
 // cleared from the context of its package.
-type _Test = dyn pb::server::TopService;
+type _Test = dyn pb::topservice_server::TopService;