CPack learned the `CPACK_PRE_BUILD_SCRIPTS`, `CPACK_POST_BUILD_SCRIPTS`,
and `CPACK_PACKAGE_FILES` variables.
The first two are lists of scripts to perform
- after pre-install files into a staging directory and before
producing the resulting packages
- after produsing the packages
The post-build script(s) also get the list of actually produced
packages in the `CPACK_PACKAGE_FILES`.
Issue: #19077
915409af49