ci: add workflow to release configuration package

[morey-tech]

This workflow will create a new Crossplane Configuration package release with a commit SHA and latest tag for each commit to main.

• It downloads the CLI directly as crossplane-contrib/xpkg-action is broken and unmaintained.
• It uses the workflow permissions to access the repo's packages.
• It will release with the same name as the existing image: showcase-configuration.

[morey-tech]

Because the package already existed, I had to go in and add actions access to it for the workflow to work.