Build and push stargz-snapshotter image usable as a kind node

[ktock]

#715

This commit adds a CI to push Kind node image to ghcr.io/stargz-containers/${VERSION}-kind namespace on each release.

• Example: ghcr.io/ktock/stargz-snapshotter:0.0.0-kind
  • https://github.com/ktock/stargz-snapshotter/actions/runs/3234126466/jobs/5296849182

$ cat /tmp/kindconfig.yaml 
kind: Cluster
apiVersion: kind.x-k8s.io/v1alpha4
nodes:
- role: control-plane
- role: worker
- role: worker
- role: worker
$ kind create cluster --config=/tmp/kindconfig.yaml --name stargz-demo --image ghcr.io/ktock/stargz-snapshotter:0.0.0-kind