Fixes #37566 - Add UEFI Secure Boot Firmware to Libvirt

[nofaralfasi]

Requires:

• https://github.com/fog/fog-libvirt/pull/155

This PR includes two commits:

1. Add firmware selection option for Libvirt VM creation.
2. Introduce a new firmware type for Secure Boot support.

When creating a new host in Foreman, after selecting Libvirt as the compute resource, a new option to select the VM's firmware will appear under the Virtual Machine tab. See the screenshot below for a demonstration:

Notes:

1. For machines created through Foreman, enrolled-keys are enabled by default when Secure Boot is activated.
2. For existing VMs, Secure Boot status is determined by the loader secure='yes' setting.

For more details: community post.