SPM support basic auth for non-git binary dependency hosts

Using Swift
74

@afarnham the steps I took and should work (with the patch above) for both users and orgs:

  1. create a private repo
  2. commit the xcframework at the root of the repo
  3. tag the repo
  4. use a https://github.com/<user>/<repo>/archive/refs/tags/<tag>.zip url

could that work for you? looking for feedback before going forward with that patch.