[JTC] Implement effort-only command interface (backport #225)

[mergify[bot]]

This is an automatic backport of pull request #225 done by Mergify. Cherry-pick of 97c94316fe9c406cf21e493cd3c58d4c1c3fd533 has failed:

On branch mergify/bp/galactic/pr-225
Your branch is up to date with 'origin/galactic'.

You are currently cherry-picking commit 97c9431.
  (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:   joint_trajectory_controller/include/joint_trajectory_controller/joint_trajectory_controller.hpp

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   joint_trajectory_controller/src/joint_trajectory_controller.cpp
	both modified:   joint_trajectory_controller/test/test_trajectory_controller.cpp
	both modified:   joint_trajectory_controller/test/test_trajectory_controller_utils.hpp

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

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