root.file_list: ignore zypper, add optional skelcd-control-SLES-for-VMware

- `yast2-registration` has been updated to use `suse-connect` as the backend, however it uses `libzypp` directly, it does not need `zypper` which is used by default when `suse-connect` is used out of Yast
- there is also `skelcd-control-SLES-for-VMware` package so use it if it is present
(so far it's the same as `skelcd-control-SLES` so it won't change anything, but it is preparation for future when SLES-for-VMware differs from standard SLES)