Upload/Downloads can't be performed using api-tokens

[migmartri]

This PR #461 added support for robot-accounts, but it's implementation didn't cover CAS related handlers in the control-plane. In practice this means that chainloop artifact upload/download don't work.

The reason that it doesn't work is because those endpoints rely on the current_user to find all the orgs available. In the case of the API-token we'll need to change that and make sure it's using the org associated with it instead.