Implement Proxmox VE (proxmoxve) Support

This issue is to track support for the Proxmox VE hypervisor, which is a free and open source KVM+Qemu platform.

The official reserved platform ID is proxmoxve, and the implementation is probably going to be mostly ripped from the ibmcloud provider to start with, as it uses the same standard for its own cloud-init data.

During Development

Create PRs addressing the following:

• Ignition (PR)
  • Add userdata fetch
  • If the platform supports it (unlikely), add userdata deletion
• Afterburn (PR)
  • (Cloud Only) Add relevant attributes
  • (Cloud Only) Add SSH key support if available
  • (Cloud Only) Add hostname support if available
  • (Cloud Only) Add check-in if needed (unlikely)
• stream-metadata-go (Add ProxmoxVE artifact to stream and release metadata stream-metadata-go#89)
  • Add platform to the Media struct in release/release.go
  • Add supporting code for new platform to toStreamArch func in release/translate.go
  • (Cloud Only) Cloud Images need to have an Images field
• (Cloud Only) stream-metadata-rust (example PR)
• fedora-coreos-tracker (metadata: add examples for proxmoxve; drop references to packet #1971)
  • Update the metadata for the new platform
• coreos-assembler (support building proxmoxve disk images coreos-assembler#4142)
  • Updated cmd-generate-release-meta
  • cosa osbuild <platform> works
• fedora-coreos-config
  • Add a stanza to platforms.yaml if the system should use a serial console, or both serial and graphical consoles
• fedora-websites-3.0 (https://gitlab.com/fedora/websites-apps/fedora-websites/fedora-websites-3.0/-/merge_requests/1068)
  • Add friendly name for platform to components/utilities/FpDownloadItem.vue
  • Add artifact to pages/coreos/download.vue
  • Possibly add logo to content/editions/coreos/home.yml
• fedora-coreos-browser (browser: add Hetzner/ProxmoxVE fedora-coreos-browser#52)
  • Add a list element for new platform in browser/index.html
• build pipeline (config: add proxmox to list of artifacts to build fedora-coreos-pipeline#1170)
  • Add platform to the list found in config.yaml for building the new artifact
• fedora-coreos-docs (example PR)
  • Add a provisioning-<platform>.adoc that walks through how to setup the new platform
  • Add an entry in the modules/ROOT/nav.adoc that points to new documentation

At Release

1. Merge upstream changes and put out a release:
   • Ignition
   • Afterburn
2. Merge metadata changes:
   • stream-metadata-go
   • stream-metadata-rust
   • fedora-coreos-tracker
   • fedora website
   • fedora-coreos-browser
3. Release updated components
   • Create and follow release checklist for stream-metadata-go
     • New release for stream-metadata-go 0.4.8 stream-metadata-go#90
   • Ensure that Dependabot has PRed stream-metadata-go into fedora-coreos-stream-generator and coreos-assembler. Merge the update PRs.
     • This can be triggered manually by navigating to fedora-coreos-stream-generator's Dependabot and coreos-assembler's Dependabot respectively, then clicking "Check for updates".
       • This might need to be done a few times, as Dependabot might not pick up tag changes for a few attempts after initial tagging.
     • build(deps): bump github.com/coreos/stream-metadata-go from 0.4.7 to 0.4.8 coreos-assembler#4152
   • Create and follow release checklist for fedora-coreos-stream-generator
4. Merge the following changes:
   • coreos-assembler
5. Wait for updates made to coreos-assembler to be propagated to latest container
   • Download latest version of coreos-assembler container. Verify platform support functionality.
6. Merge changes for:
   • Build pipeline
7. Wait for new images to reach stable then merge documentation.
   • fedora-coreos-docs merged