* Controllers should not be influenced by time jumps

Therefore use rclcpp::GenericRate<std::chrono::steady_clock> instead of
rclcpp::Rate

Signed-off-by: Martijn Buijs <martijn.buijs@gmail.com>

* Change to using `rclcpp::WallRate` for better readability

Signed-off-by: Martijn Buijs <martijn.buijs@gmail.com>