Merge topic 'cxxmodules-dyndep-error-on-private-usage' into release-3.29

3f8a59a05c cxxmodules: return failure from the collator when private usage is found

Acked-by: Kitware Robot <kwrobot@kitware.com>
Tested-by: buildbot <buildbot@kitware.com>
Merge-request: !9257