add support for --cpu-type when creating VM

[Pr0Ger]

I've tried to locally build an image to use in a cloud provider, but I figured out I can't do it since this plugin only allows creating ARM VMs (even though Parallels support running x86 VMs). This PR fixes it by allowing the override of --cpu-type when creating a VM.

One moment: since HWConfig is shared between ISO and IPSW builders, it was also added to the second one (even though it doesn't make sense since IPSW is only for macOS images built for ARM processors). I'm not sure what to do with it: should I add some extra validation to disallow passing x86 in this builder, or should I separate this parameter out of HWConfig to make it present only for the ISO builder?

[b1kjsh]

I'd definitely like to see this merged, however I think the rosetta ones run faster if I'm not mistaken. Unfortunately it's not a true environment though so this (meaning this PR) is better than not supporting x86 at all IMO.

[cjlapao]

@Pr0Ger Thanks for the PR but this is per design, if the host is ARM it will build ARM vms, if the host is x64 it will build x64 vms. We have a technical preview were we use emulation to run x64 machines on ARM, but this is still technical preview and therefore not fully available and we do not know if it will ever be. So I will leave this open in case the emulation becomes GA but until then we will keep the default behavior.

Thansk

[Pr0Ger]

@b1kjsh yeah, arm kernel + rosetta is much faster, but I want to built an image for non-local usage and most of clouds do not have arm vm

@cjlapao no problem. I'll use it from my fork until then