Systems using a template tool to generate config files
might not be effective when they see the intermediate
config files we need from the host to let certain package
managers work correctly. Therefore the cleanup code in
kiwi takes care to restore from an optionally existing
template file if no other custom variant is present.
This Fixes bsc#1163978
This commit removes the RootBind.move_to_root method as this can all be
done by using the Path.move_to_root utility method. This allows
to drop the RootBind attribute in PackageManager classes and focus
path manipulation methods into a common utility.
Related to #1281
