Add support for QEMU/KVM as hypervisor for Core

[travier-anssi]

• [x] Add KVM hypervisor host configset for the Linux kernel configuration
• [ ] Add support for virtio drivers only
• [ ] Add QEMU support
  • [ ] virtio drivers only (as much as possible)
  • [ ] Harden QEMU compilation as much as possible
• [ ] Create a systemd unit to run a QEMU instance :
  • [ ] under an unprivileged user
  • [ ] with only access to the IPsec network
  • [ ] with only RW access to a specific LV device