Fixes #24723 Direct serving of content aka HTTP redirect is not mentioned in any of the package registry specs but lots of official registries do that so it should be supported by the usual clients.
This PR adds a [CRAN](https://cran.r-project.org/) package registry. ![grafik](https://user-images.githubusercontent.com/1666336/210450039-d6fa6f77-20cd-4741-89a8-1624def267f7.png)