feat: new op type for sub-agents communication (#15556)

Add `InterAgentCommunication` for v2 agent communication

codex-rs/core/src/tasks/mod.rs

@@ -405,6 +405,7 @@ impl Session {
         turn.add_task(task);
         *active = Some(turn);
     }
+
     async fn take_active_turn(&self) -> Option<ActiveTurn> {
         let mut active = self.active_turn.lock().await;
         active.take()