core/protocol: split commands into separate files

src/client/commands/passwd_user.rs

@@ -73,7 +73,7 @@ pub async fn passwd_user(
         read_password_from_stdin_with_double_check(&args.username)?
     };
 
-    let message = Request::PasswdUser(args.username.to_owned(), password);
+    let message = Request::PasswdUser((args.username.to_owned(), password));
 
     if let Err(err) = server_connection.send(message).await {
         server_connection.close().await.ok();
@@ -81,7 +81,7 @@ pub async fn passwd_user(
     }
 
     let result = match server_connection.next().await {
-        Some(Ok(Response::PasswdUser(result))) => result,
+        Some(Ok(Response::SetUserPassword(result))) => result,
         response => return erroneous_server_response(response),
     };