Support the ability to upload to a PyPi virtual repo

So, I configured PyPi repos similar to other repo types with a local and a remote and then combined them in a virtual and set the default deployment repository as the local repo.

However, when I uploaded to the virtual repo using twine, it failed and I see the following in the logs: "Uploading to a virtual PyPI repository is not supported"

This is crazy

1. This difference is not documented on the reference documentation at all
2. This makes no sense when other repo types like docker/helm/npm/etc all are able to work this way.  This inconsistency here violates the principle of least astonishment which should be applicable to a software system
3. In my case of trying to simplify the service and URLs behind a reverse proxy I now have to figure out how to address different HTTP commands to do this routing myself (GET goes to the virtual, PUT/POST to the local).