Make sshd & sshd@ units want ssh-host-keys-migration.service
    
    Enabling the unit via the presets does not enable it on
    Silverblue/Kinoite/Sericea & IoT as we don't re-preset all units like
    it's done in Fedora CoreOS.
    
    See: https://pagure.io/workstation-ostree-config/pull-request/246
    
    Instead, have the sshd & sshd@ service unit `Wants` the
    ssh-host-keys-migration service unit so that it's pulled-in only when
    sshd is effectively enabled and in all cases.
    
    See: https://src.fedoraproject.org/rpms/fedora-release/pull-request/253
    
    See: https://bugzilla.redhat.com/show_bug.cgi?id=2172956
    See: https://src.fedoraproject.org/rpms/fedora-release/pull-request/252