Added support for VLAN and MAC VLAN interfaces plus did a bit of refactoring.

You can now create both VLAN and MAC VLAN interfaces using netlink! :+1: I've also added tests which cover the newly added functionality.

On top of that, this PR ships 

- reworked ```NetworkChangeName``` function from the original implementation which was using ```syscall```s to the one which communicates with Kernel via ```netlink```. I kept the original implementation at the bottom of the source file, though I renamed it so it's clear that it does not use ```netlink```  - the name of the function does not have "Network" prefix any more.

- refactored ```NetworkNs``` functions - both for ```PID``` and ```FD``` cases. I tried to be consistent with what we have started with the "IP" addition and deletion