List supported toolbox images

**Is your feature request related to a problem? Please describe.**

In Cockpit-podman we want to support [creating toolbox images](https://issues.redhat.com/browse/COCKPIT-1106) and further integration to allow a user to debug issues on an immutable system with a toolbox.

**Describe the solution you'd like**

We would like to be able to list supported toolbox images, toolbox offers a `--distro` and `--release` option but does not advertise which distro's and releases are supported. As a first step toolbox could list the supported Distributions using for example a new command line option `distro`:

```
$ toolbox distros
arch fedora rhel ubuntu
```

Optionally listing the container image.
```
$ toolbox distros --images
quay.io/toolbx/arch-toolbox:latest
registry.fedoraproject.org/fedora-toolbox:41
```

Or as alternative tabular output with supported versions:

```
DISTRO RELEASE
arch latest
fedora all supported releases
rhel 8.5 and newer
ubuntu all supported LTS and non-LTS releases
```

This would not help our UI, but might be useful for CLI users.

Optionally supporting machine readable json output would be nice, but not required.

This would prevent us from hardcoding the supported distributions in Cockpit-podman, we would love to also have the supported versions but this is a bit of a double edged sword. Hardcoding them in toolbox means they will get outdated quite fast, or require constant backporting to things like RHEL/Ubuntu.

I've investigated listing tags using the container registry, as we already talk to it in cockpit-podman. For example:

```
curl -X GET -s -g --no-buffer --unix-socket /run/user/1000/podman/podman.sock 'http://localhost/v1.12/libpod/images/search?term=quay.io/toolbx/ubuntu-toolbox&limit=2&listTags=true' | jq
[
{
"Index": "quay.io",
"Name": "quay.io/toolbx/ubuntu-toolbox",
"Description": "",
"Stars": 0,
"Official": "",
"Automated": "",
"Tag": "22.10"
},
```

However for Fedora this get's more messy, the endpoint does not allow sorting and the tags get appended with a `-$revision` which means I would have to implement custom filtering in the UI. Alternatively we code-ify the version format of distributions, which toolbox also knows about:

```
[jelle@t14s][/tmp]%toolbox create --distro fedora -r 23.10
Error: invalid argument for '--release'
The release must be a positive integer.
```

Fedora example tags
```
curl -X GET -s -g --no-buffer --unix-socket /run/user/1000/podman/podman.sock 'http://localhost/v1.12/libpod/images/search?term=registry.fedoraproject.org/fedora-toolbox&limit=100&listTags=true' | jq -r '.[].Tag'
38-16
38-17
37-17
38-19
37-20
38-20
41-aarch64
41-ppc64le
```

Same situation for RHEL images:
```
9.3-10
9.3-10-source
9.3-12
9.3-12-source
9.3
9.3-14
latest
9.3-14-source
```

**Describe alternatives you've considered**

In an ideal world our UI would allow any valid toolbox image in the configured container registries to be used to create a toolbox. [Podman's search API](https://docs.podman.io/en/latest/_static/api.html#tag/images/operation/ImageSearchLibpod) does not offer this functionality you can't filter on `label=com.github.containers.toolbox`.

A tool like `skopeo` can but is slow:
```
skopeo inspect docker://quay.io/toolbx/ubuntu-toolbox
{
"Name": "quay.io/toolbx/ubuntu-toolbox",
"Digest": "sha256:c0243f066ca403076318a4596aa109f0246d7c7d710cbd6e30d76c8aaf2081af",
"RepoTags": [
"22.10",
"16.04",
"22.04",
"latest",
"23.04",
"20.04",
"18.04",
"23.10"
],
"Created": "2024-04-08T00:23:33.499484028Z",
"DockerVersion": "",
"Labels": {
"com.github.containers.toolbox": "true",
"io.buildah.version": "1.23.1",
"maintainer": "Ievgen Popovych \u003cjmennius@gmail.com\u003e",
"name": "ubuntu-toolbox",
"org.opencontainers.image.ref.name": "ubuntu",
"org.opencontainers.image.version": "22.04",
"summary": "Base image for creating Ubuntu Toolbx containers",
"usage": "This image is meant to be used with the toolbox command",
"version": "22.04"
},
"Architecture": "amd64",
```

**Additional context**
Add any other context or screenshots about the feature request here. If a different tool has the functionality you're requesting, share it here.

Start by reviewing the existing toolbox command-line entry points and how `--distro` and `--release` are currently handled. Compare the proposed `toolbox distros` and `toolbox distros --images` outputs with the registry and image-tag examples in the issue. Done means agreeing on supported distributions and releases, selecting an output format, and exposing that information through a documented CLI command.

Written by the indexing model from the issue text.