Change interface export variant

[mamueluth]

Contributions via pull requests are much appreciated. Before sending us a pull request, please ensure that:

1. Limited scope. Your PR should do one thing or one set of things. Avoid adding “random fixes” to PRs. Put those on separate PRs.
2. Give your PR a descriptive title. Add a short summary, if required.
3. Make sure the pipeline is green.
4. Don’t be afraid to request reviews from maintainers.
5. New code = new tests. If you are adding new functionality, always make sure to add some tests exercising the code and serving as live documentation of your original intention.

To send us a pull request, please:

• Fork the repository.
• Modify the source; please focus on the specific change you are contributing. If you also reformat all the code, it will be hard for us to focus on your change.
• Ensure local tests pass. (colcon test and pre-commit run (requires you to install pre-commit by pip3 install pre-commit)
• Commit to your fork using clear commit messages.
• Send a pull request, answering any default questions in the pull request interface.
• Pay attention to any automated CI failures reported in the pull request, and stay involved in the conversation.

[codecov-commenter]

Codecov Report

Attention: 182 lines in your changes are missing coverage. Please review.

Comparison is base (cf405bc) 47.64% compared to head (c79ff3e) 47.15%.
Report is 26 commits behind head on master.

❗ Current head c79ff3e differs from pull request most recent head df2d739. Consider uploading reports for the commit df2d739 to get more accurate results

❗ Your organization needs to install the Codecov GitHub app to enable full functionality.

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #11      +/-   ##
==========================================
- Coverage   47.64%   47.15%   -0.50%     
==========================================
  Files          40       41       +1     
  Lines        3442     3692     +250     
  Branches     1865     1985     +120     
==========================================
+ Hits         1640     1741     +101     
- Misses        480      568      +88     
- Partials     1322     1383      +61     

Flag	Coverage Δ
unittests	47.15% <41.66%> (-0.50%)	⬇️

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

Files	Coverage Δ
...controller_interface/controller_interface_base.hpp	33.33% <ø> (ø)
..._interface/include/hardware_interface/actuator.hpp	100.00% <ø> (ø)
...re_interface/include/hardware_interface/sensor.hpp	100.00% <ø> (ø)
...re_interface/include/hardware_interface/system.hpp	100.00% <ø> (ø)
hardware_interface/src/actuator.cpp	57.01% <100.00%> (+1.56%)	⬆️
...e_interface/src/mock_components/generic_system.cpp	55.10% <100.00%> (ø)
hardware_interface/src/sensor.cpp	51.54% <100.00%> (+1.02%)	⬆️
...roller_interface/src/controller_interface_base.cpp	48.14% <0.00%> (ø)
...rface/include/hardware_interface/hardware_info.hpp	60.00% <60.00%> (ø)
hardware_interface/src/system.cpp	55.26% <50.00%> (-0.20%)	⬇️
... and 7 more