Publish a collection artifact

/kind feature

We need to publish somewhere a collection artifacts for our releases.

This should be automated as much as possible, given the already manual release process.

Possible automation source:

• prow post-submits (see kubernetes/test-infra)
• github workflows
• gitlab-ci -> not sure if viable

Possible place to upload the artefact (at least once initially, multiple could be possible):

• Ansible galaxy (pro: integration with the wider ansible ecosystem, cons: probably more work)
• github releases

Not needed for a start but nice to have:

• sign the artifacts, using sigstore -> via k/test-infra ? Not sure how artificat signing / promotion works for project under k-sigs, but I'd rather avoid handling keys ourselves if we can delegate to a trusted build service.