Could the use of private packages on ghcr.io Just Work using git credentials?

(Sorry for probably asking this nonsensically and with wrong terminology but...) We're attempting to use `wkg` to pull some WIT packages published to a private `ghcr.io` repo and hoping that it might Just Work using GitHub credentials (e.g. in `.gitconfig`). @squillace said that hypothetically this should work (on the `ghcr.io` side) and that maybe-possibly there is even some support for this already in this library, so I thought I'd ask here in case there was or it could be easily added. In the absence of this feature, to avoid creating extra steps for our devs (asking them to create new tokens and plug them into `wkg.toml`) we could just write a script to `git clone` the source registry and copy the WIT files manually, but that seems unfortunate :)

CC @sunfishcode for any extra details about what the exact workflow and commands are