Implement collection deletion

[briantist]

The v3 API has an endpoint for deleting collections: https://ansible.readthedocs.io/projects/galaxy-ng/en/latest/community/api_v3/#delete-a-collection-or-a-specific-version

We could implement this and support deleting.

I'm a little on the fence about it. I do not want to make galactory a full-fledged collection management system. We should rely on Artifactory for that.

Although deletion would necessarily rely on Artifactory's permissions and your existing auth, I could see folks wanting to disable deletion or treat this endpoint differently (like we do with publishing). I suppose we could do the exact same thing as we do for that: an option where the configured auth isn't used and you must pass in auth with the request.

For now, I consider this very low priority, since I'm primarily concerned with supporting calls used by the ansible-galaxy client for installing/downloading, and publishing.