Allow setting the analog output domain when setting an analog output (backport #1123)

[mergify]

This basically implements a service for ros-industrial/ur_msgs#30

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This is an automatic backport of pull request #1123 done by Mergify.

[mergify]

Cherry-pick of 8f2dfa9 has failed:

On branch mergify/bp/iron/pr-1123
Your branch is up to date with 'origin/iron'.

You are currently cherry-picking commit 8f2dfa9.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   ur_controllers/include/ur_controllers/gpio_controller.hpp
	modified:   ur_controllers/src/gpio_controller.cpp
	modified:   ur_robot_driver/include/ur_robot_driver/hardware_interface.hpp
	modified:   ur_robot_driver/src/hardware_interface.cpp

Unmerged paths:
  (use "git add/rm <file>..." as appropriate to mark resolution)
	deleted by us:   ur_controllers/doc/index.rst
	deleted by us:   ur_robot_driver/urdf/ur.ros2_control.xacro

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[fmauch]

Indeed for iron the necessary ros2_control xacro changes need to go to the description.

[fmauch]

Made sure this works on Iron.