common: add pve-vm-image-format standard option for VM image formats

The image formats defined for the pve-vm-image-format standard option
are the formats that are allowed on Proxmox VE storages for VM images.

Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
Reviewed-by: Daniel Kral <d.kral@proxmox.com>
Tested-by: Daniel Kral <d.kral@proxmox.com>
Link: https://lore.proxmox.com/20251113144131.560130-4-f.ebner@proxmox.com
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>

src/PVE/Storage/Common.pm

@@ -45,16 +45,31 @@ Possible formats a guest image can have.
 
 =cut
 
+PVE::JSONSchema::register_standard_option(
+    'pve-storage-image-format',
+    {
+        type => 'string',
+        enum => ['raw', 'qcow2', 'subvol', 'vmdk'],
+        description => "Format of the image.",
+    },
+);
+
+=head3 pve-vm-image-format
+
+Possible formats a VM image can have.
+
+=cut
+
 # TODO PVE 9 - Note that currently, qemu-server allows more formats for VM images, so third party
 # storage plugins might potentially allow more too, but none of the plugins we are aware of do that.
 # Those formats should either be allowed here or support for them should be phased out (at least in
 # the storage layer). Can still be added again in the future, should any plugin provider request it.
 
 PVE::JSONSchema::register_standard_option(
-    'pve-storage-image-format',
+    'pve-vm-image-format',
     {
         type => 'string',
-        enum => ['raw', 'qcow2', 'subvol', 'vmdk'],
+        enum => ['raw', 'qcow2', 'vmdk'],
         description => "Format of the image.",
     },
 );