Enabling featuregate VMExport with kubevirt

KubeVirt currently does not have the VMExport feature gate enabled in its configuration. This limits the ability to export VM disk images for backup, migration, or integration with external storage and management systems.

This issue proposes enabling the VMExport feature gate to support these scenarios using the VirtualMachineExport resource.

Once the feature gate is enabled:

• Users should be able to create VirtualMachineExport objects
• Exported VM disk images should be accessible via secure URLs
• Integration with tools or workflows that rely on disk export becomes possible