Refactor custom adapters implementation in web ui

[daudo]

I'm trying to get my feet wet with GNS 3.0.x (currently on 3.0.3), but I'm not sure if worked in 2.x

One of the things missing from the web ui is to change interface/port names, there is simply no way to edit the field:

And even worse, the names shown in the "Custom adapters configuration" Ethernet 0, Ethernet 1, .... doesn't match the port_name_format configured in the general network configuration (in my case ether{port1})

If I manually edit the gns3 file and add port_name there like this:

 "custom_adapters": [
                    {
                        "adapter_number": 0,
                        "adapter_type": "virtio-net-pci",
                        "port_name": "foobar1",
                    },
                    {
                        "adapter_number": 1,
                        "adapter_type": "virtio-net-pci",
                        "port_name": "foobar2",
                    },

... the names show when creating new connections, but as soon as I edit the device configuration via the web UI, those port_name entries are lost again.