ROS2 port yocs_velocity_smoother - TODO

[clalancette]

405 is a first port of the velocity_smoother to ROS 2. It ports the main bulk of the code, but there are several things left to do:

• [x] Create example parameter files for ROS 2
• [x] Port the launch files to ROS 2
• [x] Create an example composable launch file for ROS 2
• [ ] Port the tests to ROS 2
• [ ] Test the package in a complete system