Osbuild should create network installer options during the compose process

[pcdubs]

Describe the bug

Since moving to osbuild for our installer, we no longer produce the network installer bits needed for things like PXE boot or HTTP boot.

Example in Fedora 39:
https://kojipkgs.fedoraproject.org/compose/iot/Fedora-IoT-39-20240118.0/compose/IoT/x86_64/os/

Now in Fedora 40:
https://kojipkgs.fedoraproject.org/compose/iot/Fedora-IoT-40-20240118.0/compose/IoT/x86_64/

Included on the osbuild produced installer iso:

EFI
└── BOOT
    ├── BOOTAA64.EFI
    ├── fonts
    │   └── unicode.pf2
    ├── grubaa64.efi
    ├── grub.cfg
    └── mmaa64.efi
images
├── efiboot.img
├── install.img
└── pxeboot
    ├── initrd.img
    └── vmlinuz

Missing from F40 is the boot.iso. F39 boot.iso.

[nullr0ute]

In the lorax world this was generated as part of the ISO install build process but there's no reason why it couldn't/shouldn't be a separate artifact.

[pcdubs]

osbuild/images#394

[mmartinv]

After discussing this with osbuild members it looks like we would need to create a new image type where we don't include the ostree commit and probably try to minimize the anaconda installer size (osbuild/images#409). To do that we would need to provide a new stage for osbuild to allow the removal of files from the filesystem tree.

[7flying]

@mmartinv please create a follow-up issue as the result of your investigation