Make UTM Remote able to connect to standard Libvirt over TCP or SSH

[irusensei]

Hi. This is somewhat related to #4630 which didn't seem to have got a lot of visibility.

Basically, it would be great to either have the UTM Remote App be able to connect to a Linux server running Libvirtd on Linux (or anything Libvirt in general). Reason behind it is that sometimes you need some good old x86 cruft to run as native as possible. KVM virtual machines also have a lot more capabilities than what's available on MacOS hypervisor.

As of today, there is no proper implementation of virt-manager to iOS and MacOS. Virt-manager runs but it's very janky and the very few remote clients seems to be very niche (just spice, just proxmox) don't seem to be actively maintained. UTM Remote seems like a great way to fill that gap. Of course I wouldn't expecting the VMs to be fully configurable through UTM remote.

I'm totally fine having this feature being locked behind a paid purchase.

Thank you.