Add dracut bundle

[DaanDeMeyer]

Dracut is used for generating unified kernel images which can be signed for use by Secure Boot. dracut itself requires binutils (objcopy) for generating unified kernel images.

See https://systemd.io/BOOT_LOADER_SPECIFICATION/#type-2-efi-unified-kernel-images

To add a little more context, I'm working on unifying mkosi's distros a bit more. One part of that is making unified kernel images work on all of them using dracut and kernel-install. Clear Linux is the last remaining distro that's failing in CI because of the lack of dracut in the core-os-plus bundle. The sysadmin-basic bundle contains too much stuff for use as a baseline in mkosi which is why I propose adding a new dracut bundle to make this use case work.