Add emerging platforms process/flow

[travier]

Describe the enhancement

Add a lighter process to add a new supported platform for Fedora CoreOS.

The idea is that for lightly supported platforms we do the Ignition and Afterburn integration work and we stop there. Notably we do not produce disk images.

We then document a procedure to take one of our exiting image and tweak it to get a valid disk image for the new platform.

This would significantly reduce the overhead of adding new platform to Fedora CoreOS while keeping it reasonably low effort for users to setup FCOS on their favorite platform.

See PR for this process in #1562

System details

N/A

Additional information

Previous discussion in #719

[travier]

Platforms that are candidate for this process:

• Hetzner: Platform Request: Hetzner #1324
• Oracle Cloud: Platform Request: Oracle Cloud Infrastructure (OCI) #414
• Scaleway: Platform Request: Scaleway #866
• OVHcloud: Platform Request: OVHcloud (formerly named OVH) #666

Basically any platform already supported by cloud-init could be considered (https://github.com/canonical/cloud-init/tree/main/cloudinit/sources.).

[jlebon]

We discussed this in today's community meeting:

AGREED: We generally like the idea of "emerging" platforms. We will continue fleshing out the UX and communications part of it in the ticket. (jlebon, 17:05:29)

[travier]

We now have this flow as of #1562. We'll keep iterating and I'll close this one as it does not need immediate action.