handover_detector & gripper_position_detector should be part of the gripper, not the arm #1249
Description
The `handover_detector` can be ignored in this project, but `gripper_position_detector` should be modelled correctly. It doesn't mean it should be done correctly right now in this PR. But it should be done correctly soon.
Originally posted by @MatthijsBurgh in #1239 (comment)