feat: add GNOME desktop-hypervisor dish for BIOS laptops

- storage/biosboot.ks: GPT disk label with a 2 MiB BIOS boot partition,
  no ESP (pure legacy layout); registered as the 'biosboot' storage choice
- recipe_templates.yaml: make the desktop hypervisor a superset of the
  base hypervisor so GNOME hypervisor dishes get libvirtd + virt-manager
- recipes_manifest.yaml: enable the desktop-hypervisor group targeting
  Fedora 44 (gnome, biosboot, grub, security enabled, gnome initial-setup,
  hardware-support, intelcpu)
- initial-setup/gnome/config.ks: apply the vendor.conf fix (truncate and
  append skip=privacy / providers=local-first!) as an enabled %post
- tests: update BASE_FRAGMENTS fixture to core-explicit.ks (follow-up to
  ccf4f9d)

cook/recipe_templates.yaml

@@ -35,6 +35,7 @@ choices:
   storage:
     standard: storage/standard.ks
     encrypted: storage/encrypted.ks
+    biosboot: storage/biosboot.ks
   bootloader:
     grub: bootloader/grub.ks
     systemd-boot: bootloader/systemd-boot.ks
@@ -60,6 +61,9 @@ features:
       - hypervisor/base/services.ks
       - hypervisor/base/post-scripts.ks
     desktop:
+      - hypervisor/base/packages.ks
+      - hypervisor/base/services.ks
+      - hypervisor/base/post-scripts.ks
       - packages/virtual-machine-manager/packages.ks
       - packages/virtual-machine-manager/post-scripts.ks
   hypervisor_type: