Make magento/product-community-edition available on GitHub

Currently is not possible to see the differences between versions for magento/product-community-edition composer virtual package (and enterprise as well). For a custom project, requiring magento/product-community-edition directly is not viable because unwanted packages are added by it, so instead we copy the require section into our own composer.json and remove what we need. But this quite an extensive task to get them every time a new version is released, since several modules have their versions bumped.

Preconditions

None

Steps to reproduce

None

Expected result

1. Have magento/product-community-edition's composer.json definition available on GitHub, with all applicable tags, so we can diff the composer.json between all the released versions;
2. Bonus: have magento/product-community-edition available on Packagist.org;
3. Bonus: have magento/product-enterprise-edition available on GitHub (and/or Packagist.org) if applicable/allowed;

Actual result

magento/product-community-edition definition is not available anywhere public.

Original Report: https://github.com/magento/magento2/issues/13749 by @kassner

Start by reviewing community-features issue #62 and the linked original report #13749 to understand the package publication constraints. Done means the community package definition is publicly available with applicable release tags for version diffs; the enterprise and Packagist requests are bonus scope.