Support sending the FortiGate interface subnet list to EMS

In order to allow FortiClient EMS to share FortiClient information based on IP subnet mask, the FortiGate must send its interface IP and netmask to EMS. This enhancement allows the FortiGate to include its IP and netmask information in the gateway-mac-request.

To view the gateway MAC REST API output:

# diagnose endpoint fctems json gateway-mac-request 
JSON:
"""
{
  "gateway_mac_list":[
    {
      "ip_list":[
        "10.6.30.4"
      ],
      "ip_subnet_list":[
        {
          "gateway_ip":"10.6.30.4",
          "netmask":"255.255.255.0"
        }
      ],
      "mac":"00:0c:29:8f:c5:19",
      "vdom":"root",
      "interface":"port1",
      "sn":"FGVM32TM22000***"
    },
    {
      "ip_list":[
        "10.1.100.4"
      ],
      "ip_subnet_list":[
        {
          "gateway_ip":"10.1.100.4",
          "netmask":"255.255.255.0"
        }
      ],
      "mac":"00:0c:29:8f:c5:23",
      "vdom":"root",
      "interface":"port2",
      "sn":"FGVM32TM22000**"
    }
  ]
}
"""