expose get_data_type method in loaned interfaces (backport #2351)

[mergify]

This is needed if the user wants to query in the controller code

---

This is an automatic backport of pull request #2351 done by Mergify.

[mergify]

Cherry-pick of 7f92700 has failed:

On branch mergify/bp/jazzy/pr-2351
Your branch is up to date with 'origin/jazzy'.

You are currently cherry-picking commit 7f92700.
  (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:   hardware_interface/include/hardware_interface/actuator_interface.hpp
	modified:   hardware_interface/include/hardware_interface/system_interface.hpp

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   hardware_interface/include/hardware_interface/loaned_command_interface.hpp
	both modified:   hardware_interface/include/hardware_interface/loaned_state_interface.hpp

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

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 88.66%. Comparing base (17d82e6) to head (5b88b68).
Report is 3 commits behind head on jazzy.

Additional details and impacted files

@@            Coverage Diff             @@
##            jazzy    #2357      +/-   ##
==========================================
- Coverage   88.68%   88.66%   -0.03%     
==========================================
  Files         145      145              
  Lines       16745    16744       -1     
  Branches     1442     1442              
==========================================
- Hits        14851    14846       -5     
- Misses       1335     1339       +4     
  Partials      559      559              

Flag	Coverage Δ
unittests	88.66% <100.00%> (-0.03%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
.../include/hardware_interface/actuator_interface.hpp	90.96% <100.00%> (ø)
...de/hardware_interface/loaned_command_interface.hpp	52.50% <ø> (-7.50%)	⬇️
...lude/hardware_interface/loaned_state_interface.hpp	60.00% <ø> (ø)
...ce/include/hardware_interface/system_interface.hpp	84.26% <100.00%> (ø)

... and 2 files with indirect coverage changes

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[christophfroehlich]

Isn't this breaking ABI somehow, are we fine with that on jazzy?

[christophfroehlich]

nvmd, ABI checker is happy so am I.