chore: bring images up to date

[casibbald]

Summary

This PR brings image naming, workflows, and references in line with the current Liquid Metal setup: registry detection for forks, ARM (experimental) workflows, explicit architecture suffixes on image names, and the move from weaveworks-liquidmetal to liquidmetal-dev.

Successful builds can be found here:

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1. Registry detection (fork-friendly)

• Workflows now push to the repository owner's GHCR by default:
  • REGISTRY=ghcr.io/${{ vars.REGISTRY_OWNER || github.repository_owner }}
• So forks (e.g. microscaler/image-builder) publish to ghcr.io/microscaler/..., and upstream to ghcr.io/liquidmetal-dev/....
• Optional repo variable REGISTRY_OWNER overrides the owner (e.g. for a different org).
• Applied in: kernel-images.yml, kernel-images-manual.yml, capmvm-kubernetes-manual.yml.

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2. Kernel workflows and images

• workflow_dispatch added to Build and release kernel images for manual runs.
• Kernel image names now include architecture:
  • amd64: firecracker-kernel-amd64, firecracker-kernel-bin-amd64, firecracker-kernel-modules-amd64; cloudhypervisor-kernel-amd64, cloudhypervisor-kernel-bin-amd64, cloudhypervisor-kernel-modules-amd64.
  • arm64 (experimental): firecracker-kernel-arm64, firecracker-kernel-bin-arm64, firecracker-kernel-modules-arm64.
• New kernel 5.2.21 configs and build for Firecracker (x86 + experimental ARM); Cloud Hypervisor keeps 5.12 and 5.15.12.
• Firecracker kernel clone URL switched from git:// to https:// for CI.
• ARM kernel workflow added: .github/workflows/kernel-images-arm.yml (push on experimental/arm/kernel/**, manual dispatch, QEMU + Buildx for linux/arm64).

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3. CAPMVM workflows and images

• CAPMVM image names aligned with architecture:
  • amd64: capmvm-k8s-ubuntu-{20.04|22.04|24.04}-amd64
  • arm64 (experimental): capmvm-k8s-ubuntu-{20.04|22.04|24.04}-arm64
• ARM CAPMVM workflow added: .github/workflows/capmvm-kubernetes-arm-manual.yml (manual dispatch, same inputs as x86: k8s version, containerd, Ubuntu version).
• Experimental ARM CAPMVM Dockerfile/Makefile aligned with x86: pkgs.k8s.io repo, KUBERNETES_MAJOR_MINOR / KUBERNETES_FULL_VERSION, package version -1.1, and OS_VERSION for Ubuntu choice.

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4. References: weaveworks-liquidmetal → liquidmetal-dev

• All image and GitHub references updated from weaveworks-liquidmetal to liquidmetal-dev (default REGISTRY, README examples, and links to flintlock, cluster-api-provider-microvm, site, microvm-action-runner).
• Makefile default REGISTRY is now ghcr.io/liquidmetal-dev where applicable.

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Files changed (22)

• Workflows: kernel-images.yml, kernel-images-manual.yml, new kernel-images-arm.yml, capmvm-kubernetes-manual.yml, new capmvm-kubernetes-arm-manual.yml.
• Kernel: Makefile (amd64 names), firecracker/base Dockerfile (https), new configs (5.2.21 x86 + ARM, 5.15.12 CH), README.
• Experimental ARM: kernel Makefile (arm64 names), firecracker base Dockerfile (https), capmvm Dockerfile + Makefile (pkgs.k8s.io, version args), READMEs; github-action-runner Makefile + README.
• CAPMVM: Makefile (amd64 image name), README.
• Root README (publishing/registry and REGISTRY_OWNER example).