Splits the definitions into two dicts, while joining then for now to
preserve the downloads dict.
Update all consumers of the variables, which are roughly:
- manual includes of the download role (which will be removed in the
short future)
- install tasks using the resolved 'dest' to find the artefacts
This will make further division of the downloads role easier.
* Validate systemd unit files
This ensure that we fail early if we have a bad systemd unit file
(syntax error, using a version not available in the local version, etc)
* Hack to check systemd version for service files validation
factory-reset.target was introduced in system 250, same version as the
aliasing feature we need for verifying systemd services with ansible.
So we only actually executes the validation if that target is present.
This is an horrible hack which should be reverted as soon as we drop
support for distributions with systemd<250.