CPU Isolation

[ArnauGabrielAtienza]

Allow users to reserve CPUs for host operations and restrict VM execution to the remaining CPUs. Apply the VM CPU set to machine.slice through AllowedCPUs, while leaving system.slice and user.slice unrestricted.

[sk4zuzu]

Finally! 👍🥰

So here's some code that does that #243. In addtiion to this I think we should introduce 2 more slices infra.slice and dpdk.slice to fully isolate them form libvirt and the OS. 🤔

[sk4zuzu]

But I think we need another bigger / compound PR that handles all 3 slices at once, ie. infra dpdk machine. After that is done we could finally think about automated limit calculation (for example in DPDK case). 🤔