[WIP] Fixes #6444 - add support for virtual NICs

The thing is that parser just goes over facts and parses them by name, so 'whatever_eth0' will result in hash with key 'whatever'. There's no logic around link fact there. Host is the one that can detect existing link fact attribute and set model attribute accordingly if it exists. Anyway I added new commit with the code so you can see what I mean. Let me know if I should remove it or leave it there. I think it is testing something like "if I don't give it a key, it won't parse it".