networkctl: Add support to display SIP servers

networkctl: Add support to display SIP servers

```
❯ build/networkctl status veth99                                                                                                                                                           ─╯
● 17: veth99
                     Link File: /usr/lib/systemd/network/99-default.link
                  Network File: /usr/lib/systemd/network/veth99.network
                          Type: ether
                         State: routable (configured)
                        Driver: veth
                    HW Address: 1e:04:f8:b8:2f:d4
                           MTU: 1500 (min: 68, max: 65535)
                         QDisc: noqueue
  IPv6 Address Generation Mode: eui64
          Queue Length (Tx/Rx): 1/1
              Auto negotiation: no
                         Speed: 10Gbps
                        Duplex: full
                          Port: tp
                       Address: 192.168.5.35 (DHCP4)
                                fe80::1c04:f8ff:feb8:2fd4
                       Gateway: 192.168.5.1
                           DNS: 192.168.5.1
                           NTP: 192.168.5.1
                           SIP: 192.168.5.4
                                192.168.5.5
                     Time Zone: Europe/Berlin

Mar 21 23:26:32 Zeus systemd-networkd[671]: veth99: Link DOWN
Mar 21 23:26:32 Zeus systemd-networkd[671]: veth99: Lost carrier
Mar 22 10:25:35 Zeus systemd-networkd[671]: veth99: Link UP
Mar 22 10:25:35 Zeus systemd-networkd[671]: veth99: Gained carrier
Mar 22 10:25:36 Zeus systemd-networkd[671]: veth99: Gained IPv6LL
Mar 22 10:29:02 Zeus systemd-networkd[671]: veth99: Link DOWN
Mar 22 10:29:02 Zeus systemd-networkd[671]: veth99: Lost carrier
Mar 22 10:29:13 Zeus systemd-networkd[671]: veth99: Link UP
Mar 22 10:29:13 Zeus systemd-networkd[671]: veth99: Gained carrier
Mar 22 10:29:14 Zeus systemd-networkd[671]: veth99: Gained IPv6LL

```