Add CI to force sync build-configs and module-definitions
Currently, the kde-builder's build-configs files are just in another format, and their contents are equal to the ksb module-definitions.
Let's introduce a CI check for now, that will fail in case people forget to update the build-configs. So people get used to that they need to edit both paths.
For example, after this commit, the two contents got outsynced. And this will be in the job log:
dev is not equal 0.8.x
/builds/sysadmin/repo-metadata/module-definitions/custom-qt6-libs.ksb /builds/sysadmin/repo-metadata/build-configs/custom-qt6-libs.yaml
Later, when kde-builder will differ the content of build-configs, this script can be removed.