Download URL redirect for privacy and download counter

[viktorix]

Is your feature request related to a problem? Please describe.
Right now the download URL for the plugins/themes is a direct GitHub link. Whenever we integrate this into core, each ClassicPress website downloading a plugin/theme will be logged by GitHub (Microsoft). This poses a potential privacy issue.

Describe the solution you'd like
We need to set up a download URL that's basically a redirect to the GitHub download URL, but it doesn't contain any personal website information to be logged by GitHub. So we protect users' privacy.

While we set this up, we should add a simple download counter to keep track of plugin/theme downloads. A simple counter without any personal website details. Each request to download plugin/theme would increment the counter by 1. This will help ClassicPress and developers better understand how many downloads their items have.

So if the download URL is:
https://github.com/azurecurve/azrcrv-taxonomy-index/releases/download/v1.2.3/azrcrv-taxonomy-index.zip

The directory would replace https://github.com with something like this:
https://directory.classicpress.net/download/azurecurve/azrcrv-taxonomy-index/releases/download/v1.2.3/azrcrv-taxonomy-index.zip