- update: database client to implement a database trait so we can mock it out

- update unit tests
- add: database client mock

auth-service/src/main.rs

@@ -3,6 +3,7 @@ use std::env;
 use tonic::transport::Server;
 use auth_service::grpc::MyAuthService;
 use auth_service::database_client::DatabaseClient;
+use auth_service::database_client::DatabaseClientTrait;
 use auth_service::auth::auth_service_server::AuthServiceServer;
 
 pub mod auth {