Feature request

Feature description

I would be surprised if I'm the first one to bring up this discussion but I didn't find it anywhere. Why aren't we using the recommended Tree::sleep() from BT.CPP instead of the ROS rclcpp::WallRate to leverage event-driven trees?

I guess an obvious reason would be the better integration of rclcpp::WallRate with simulation time. But shouldn't we thrive to have all the benefits that both offer?

In a couple of instances we use emitWakeUpSignal, but afaik these should be useless without Tree::sleep() right @facontidavide?

Implementation considerations