Support non-browsable registries, such as ghcr.io

[garrett]

You're supposed to be able to put in any image, including ghci.io in the image dropdown on "Create container" and have it work.

Trying any container image from ghcr.io (GitHub's registry) causes an error:

Error message: Failed to search for images: 1 error occurred: * couldn't search registry "ghcr.io": Requesting bearer token: invalid status code from registry 403 (Forbidden) "

Cockpit Podman is supposed always allow using a URI fragment to an image regardless of if a registry is browsable or not.

Example containers that do not work:

• Homarr dashboard: ghcr.io/ajnart/homarr:latest
• GitHub Pages: ghcr.io/github/pages-gem

[garrett]

Screenshot:

[garrett]

Oh, this is a duplicate of #1220