Add ability to set artifactType at the image index level

[ipanova]

Feature request description

Based on the OCI image-spec image index can contain artifactType field. . With the current podman version (5.1.2) it is possible to set this field only for child manifest via podman manifest add --artifact-type

Suggest potential solution

Add ability to set artifactType field at the image index level. For example at creation step podman manifest create --artifact-type

Have you considered any alternatives?

A clear and concise description of any alternative solutions or features you've considered.

Additional context

Add any other context or screenshots about the feature request here.

[mheon]

We are adding a dedicated set of artifact-handling commands. This should be part of them. @baude FYI

[github-actions[bot]]

A friendly reminder that this issue had no activity for 30 days.

[baude]

with podman 5.4 we now have artifact support as a "verb" in podman (i.e. podman artifact --help). I believe we can do what you are asking for there. Consider:

❯ podman artifact add --type foo/octet-bar quay.io/foo/bar:latest ~/homer.gz 
b82cf7213838dff3fa2bc19d6226ecef2d671e38b0ab7aab49e0b9353c56dd92

podman on  issue25435 [?] via 🐹 v1.23.6 via 🐍 v3.13.2 
❯ podman artifact inspect quay.io/foo/bar:latest 
{
     "Manifest": {
          "schemaVersion": 2,
          "mediaType": "application/vnd.oci.image.manifest.v1+json",
          "artifactType": "foo/octet-bar",
          "config": {
               "mediaType": "application/vnd.oci.empty.v1+json",
               "digest": "sha256:44136fa355b3678a1146ad16f7e8649e94fb4fc21fe77e8310c060f61caaff8a",
               "size": 2,
               "data": "e30="
          },
          "layers": [
               {
                    "mediaType": "application/x-gzip",
                    "digest": "sha256:e85b7050cdb9088f19958c33a0308647261d0829db4f7572509c922b1d3d287f",
                    "size": 12584856,
                    "annotations": {
                         "org.opencontainers.image.title": "homer.gz"
                    }
               }
          ]
     },
     "Name": "quay.io/foo/bar:latest",
     "Digest": "sha256:b82cf7213838dff3fa2bc19d6226ecef2d671e38b0ab7aab49e0b9353c56dd92"
}

I'm closing this PR because of this. Feel free to file an issue against the new commands if you feel this does not accomplish what you want.