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/recipes_manifest.yaml

@@ -46,15 +46,16 @@ recipes:
         guest-agents: false
         hypervisor: base
         hypervisor_type: intelcpu
-#
-#  # Desktop-hypervisor variants
-#  - name: desktop-hypervisor
-#    variants:
-#      - repository: 43
-#        desktop: gnome
-#        storage: standard
-#        bootloader: grub
-#        hardware-support: false
-#        guest-agents: true
-#        hypervisor: desktop
-#        hypervisor_type: ["amdcpu", "intelcpu"]
+  # Desktop-hypervisor variants
+  - name: desktop-hypervisor
+    variants:
+      - repository: "44"
+        desktop: gnome
+        storage: biosboot
+        bootloader: grub
+        security: enabled
+        initial-setup: gnome
+        hardware-support: true
+        guest-agents: false
+        hypervisor: desktop
+        hypervisor_type: intelcpu