Add velocity and acceleration scaling functionality

[cpr-fer]

While this compiles and looks like the correct way to interact with the limits the scaling fails with the error "It looks like the planner did not set the group the plan was computed for".

This occurs in this file: https://github.com/ros-planning/moveit2/blob/humble/moveit_core/trajectory_processing/src/iterative_time_parameterization.cpp

[cpr-fer]

Turns out the planning group has to be passed in the RobotTrajectory objects constructor to make it work. The vacuum examples pick and place vertical motions are now successfully slowed.