make detail symbols hidden

[adlarkin]

Signed-off-by: Ashton Larkin [email protected]

Summary

After noticing that a detail class in ign-gazebo was not marked as hidden (gazebosim/gz-sim#759), I looked through the other ignition repositories and found that there are a few detail symbols in ign-physics that should be marked as hidden as well.

Checklist

• Signed all commits for DCO
• Added tests
• Updated documentation (as needed)
• Updated migration guide (as needed)
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• All tests passed (See
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[adlarkin]

@j-rivero I'm already seeing some issues in CI: https://github.com/ignitionrobotics/ign-physics/pull/250/checks?check_run_id=244178102

I'm not sure what we need to do here, but @chapulina mentioned: "We should be able to hide all the details without thinking twice. If this causes some issue on tests or examples, this probably means that those classes shouldn't be in detail."

[scpeters]

@j-rivero I'm already seeing some issues in CI: https://github.com/ignitionrobotics/ign-physics/pull/250/checks?check_run_id=244178102

I'm not sure what we need to do here, but @chapulina mentioned: "We should be able to hide all the details without thinking twice. If this causes some issue on tests or examples, this probably means that those classes shouldn't be in detail."

from the CI results, it looks like we can't hide detail headers