Use Alpine's QEMU for "pmbootstrap qemu"

Created by: ollieparanoid

We want to use Alpine's Qemu for launching the VM, so we can avoid dealing with various QEMU versions/configurations shipped with the host distributions.

TODO:

• Fork Alpine's QEMU package, and add virgl (#543 (closed)) and SDL2 support
• Run Alpine's QEMU as proof of concept from the host OS like shown here
  • Headless version (for --spice)
  • SDL2 version
  • GTK version
• Adjust pmbootstrap qemu:
  • install the right QEMU package in the native chroot (depends on the VM architecture)
  • Run --spice with Alpine's QEMU
  • Run GTK and SDL2 with Alpine's QEMU
• Proper upstreaming
  • Upstream changes to Alpine's QEMU package
  • Remove our fork of the package