Add packages needed to build secureboot/ generate certs

[fwilhe]

What happened:

Tried building the _secureboot image variant and it failed due to missing commands

What you expected to happen:

I should be able to build the _secureboot image using ./build aws_secureboot_dev

The following packages/commands should be in the image:

• efi-tools: cert-to-efi-sig-list
• uuid-runtime: uuidgen

How to reproduce it (as minimally and precisely as possible):

Anything else we need to know:

Environment:

[fwilhe]

Unclear if this package should be part of the dev image? https://github.com/awslabs/python-uefivars, cf: https://github.com/gardenlinux/gardenlinux/blob/a2644846d713501989c6293ae9f0e78edbeefbdb/docs/02_operators/deployment/aws-secureboot.md?plain=1#L107C3-L107C45

Seems to be needed for creating the certificates for secure boot