Fixes #37566 - Add UEFI Secure Boot Firmware to Libvirt

[nofaralfasi]

Requires:

• EFI & Secure Boot fog/fog-libvirt#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.

[nofaralfasi]

Failing tests should be fixed automatically after fog/fog-libvirt#155 is merged.

[nofaralfasi]

As noted in my comment on the VMware-related PR #10324 (comment), the same issue occurs with Libvirt. The Automatic firmware selection is not functioning correctly on the compute_attributes form.

[adamruzicka]

Is there a reason for having strings as keys in the inner hash?

[nofaralfasi]

Yes, the reason for using strings as keys here is that Libvirt expects these values in this format and converts them to XML accordingly. You can see this conversion in the Libvirt code here. For more details, refer to the related PR.