Merge topic 'iface-public-modules' into release-3.30

854eba0c53 target_sources: Improve error message for CXX_MODULES on INTERFACE libraries
cd179e7560 Tests/RunCMake/CXXModules: Rename FileSetModules cases to be more specific

Acked-by: Kitware Robot <kwrobot@kitware.com>
Merge-request: !10090