add blacklist option for overlay pkgs
Created by: philmmanjaro
Having a excludelist option for the sync-folder not to get certain packages from our upstream project Archlinux we may need to add also a blacklist option for our overlay packages, to hold some back within our snap function. This would give us the option to test or release packages to a certain branch but only hold it there.
As a workaround the xperimental branch got introduced to experiment with new packages without changing the current workflow of our distro.