Fixes #28888 - add cert auth for docker registry

[jlsherrill]

No description provided.

[wbclark]

Per @jlsherrill this adds cert auth for the Katello docker registry API. This was done by the forklift playbook previously used by the Katello team and never made it into the puppet modules. Pulp2 Capsule syncs for Docker would go to port 5000 and didn't require cert auth, therefore this only really needs to be present when pulpcore is enabled but isn't hurting anything otherwise.

[jlsherrill]

Yep, this /v2/ api is the docker registry that katello provides (that is backed by pulp). These end points need to support cert-based auth in order for a foreman proxy content to be able to sync from it.

[wbclark]

ACK. My first thought was that this should be conditional on pulpcore and its docker plugin being enabled, but this Katello API will do nothing except in that case so just adding cert auth support for it without making it conditional should be fine.

[jlsherrill]

Thanks @wbclark !