Add OS image release workflow

[darkowlzz]

This workflow can be used to build all the OS images in parallel and
publish them together.

Duplicate configurations due to lack of YAML anchors support in github actions, refer: https://github.saobby.my.eu.orgmunity/t/support-for-yaml-anchors/16128/39

[darkowlzz]

Ran this on my fork:

All the ubuntu images (18.04 and 20.04) in the same job took ~9 minutes:

The whole thing took ~10 minutes:

Manually verified that the manifest lists are updated properly:

$ docker manifest inspect ghcr.io/darkowlzz/ignite-ubuntu:18.04
{
   "schemaVersion": 2,
   "mediaType": "application/vnd.docker.distribution.manifest.list.v2+json",
   "manifests": [
      {
         "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
         "size": 1777,
         "digest": "sha256:88417a2968be3fa36cc4d57405a07f9d0e714f2899fa792a675908e976db9ad5",
         "platform": {
            "architecture": "amd64",
            "os": "linux"
         }
      },
      {
         "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
         "size": 1988,
         "digest": "sha256:616646f6463b92eb83adbd9006677b2d2bba609c81fdaa04d4541948d35fed51",
         "platform": {
            "architecture": "arm64",
            "os": "linux"
         }
      }
   ]
}
...
$ docker manifest inspect ghcr.io/darkowlzz/ignite-kubeadm:v1.18.3
{
   "schemaVersion": 2,
   "mediaType": "application/vnd.docker.distribution.manifest.list.v2+json",
   "manifests": [
      {
         "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
         "size": 2823,
         "digest": "sha256:c46bbc6ecc2a9b20b06433cc7d1cbc6197cdfe80fc9a7744e80b23ba0e1e2cea",
         "platform": {
            "architecture": "amd64",
            "os": "linux"
         }
      },
      {
         "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
         "size": 2823,
         "digest": "sha256:8ed6ff5bb11061cb20c3d2197eb943dc745eca55e44fdacbd392035721970f84",
         "platform": {
            "architecture": "arm64",
            "os": "linux"
         }
      }
   ]
}