gns3: set default interface names in appliance file

[troglobit]

For testing in virtual environments, it would be highly useful if the interface names were the same as final HW. The GNS3 appliance files support an "port_name_format": "ethernet{port1}" format. There's also a "first_port_name" that could be useful in some use-cases.

For more info, see:

• https://www.google.com/search?q=gns3a+%22port_name_format%22+gns3+schema&client=firefox-b-lm&sca_esv=5d0811d5ae0715ef&sca_upv=1&sxsrf=ACQVn0_ZgUef_YX7nv0GuzH4P6jd78NFHQ%3A1713889254198&ei=5t8nZpHiC_DGwPAP67CXqAg&udm=&ved=0ahUKEwiR7biB39iFAxVwIxAIHWvYBYUQ4dUDCA8&uact=5&oq=gns3a+%22port_name_format%22+gns3+schema&gs_lp=Egxnd3Mtd2l6LXNlcnAiJGduczNhICJwb3J0X25hbWVfZm9ybWF0IiBnbnMzIHNjaGVtYTIHECEYoAEYCkjHXFD5AljPWnABeACQAQCYAXWgAfcIqgEDNy41uAEDyAEA-AEBmAIMoAKPCcICBRAhGKABmAMAiAYBkgcDNy41oAe6Jw&sclient=gws-wiz-serp
• https://raw.githubusercontent.com/GNS3/gns3-registry/master/appliances/cisco-vWLC.gns3a
• https://gns3-server.readthedocs.io/en/stable/file_format.html
• http://www.freertr.org/rtr-x86_64.gns3a