networkd: report error if lease file cannot be loaded and ignore

networkd: report error if lease file cannot be loaded and ignore

On my system, networkd would report that interface ve-rawhide is "Failed"
without anything in the logs:
systemd-networkd[651095]: ve-rawhide: Trying to reconfigure the interface.
systemd-networkd[651095]: ve-rawhide: Gained IPv6LL
systemd-networkd[651095]: ve-rawhide: Link DOWN
systemd-networkd[651095]: ve-rawhide: Lost carrier
systemd-networkd[651095]: ve-rawhide: Configuring with /usr/lib/systemd/network/80-container-ve.network.
systemd-networkd[651095]: ve-rawhide: Link UP
systemd-networkd[651095]: ve-rawhide: Gained carrier
systemd-networkd[651095]: ve-rawhide: Failed

At debug level:
systemd-networkd[799993]: dhcp-server-lease/ve-rawhide:1:1: Missing object field 'Address'.

$ jq </var/lib/systemd/network/dhcp-server-lease/ve-rawhide
{
  "BootID": "5d86b34b98894322bfd4ae8443ce59b3",
  "Leases": [
    {
      "ClientId": [ ... ],
      "Address": [ 192, 168, 120, 179 ],
      "Hostname": "rawhide",
      "ExpirationUSec": 966046821158,
      "ExpirationRealtimeUSec": 1711203197266940
    }
  ]
}

I'm not sure why "Address" is missing, but anyway, in this case, we should ignore the
lease file rather than refusing to configure the interface. Also, warn at the point
where we know what the filename is.