[Manipulator] Add forward_command_controller

[Jelmerdw]

Summary

At the moment, we only have a joint_trajectory_controller for our manipulators.
We would like to add a forward_command_controller (position, velocity) for tasks like joystick control or teleoperation.

DOD:

• Add new controller
• Works in simulation
• Test on Franka hardware
• Test on UR hardware
• Documentation up-to-date
• Possibly change our standard demo to use this controller.
• Reviewed

Motivation

Why this feature is useful or necessary.

Describe Alternatives

Are there other approaches that were considered?

Additional Context

Related issues, links, or references.