F #158: Add Alpine, VRouter, OneKE arch64 images

- x86_64 remains bios based
- aarch64 is UEFI only (no bios support)
- couldn't get Alpine aarch64 installation from CD to boot properly,
  switching to nocloud cloud-init images
- 256MB too small for aarch64, failed during build
- using Packer/Qemu `firmware` option (instead efi_firmware_code/vars)
  works for both bios & EFI, this still allows use single Packer
  template for both arch
- adopt VRouter
- OneKE for aarch64 requries further work, preps only, no targets