We update the following items in build/pkgs/sagelib/src/:

• Add README.rst
• Add LICENSE.txt (for sagelib and documentation only - see discussion in Install COPYING.txt #21571)
• setup.py metadata (author, license, compatibility, ....)

We switch from distutils to setuptools so we can put the new metadata in the setup.cfg format.

sage-devel post regarding naming:

• https://groups.google.com/g/sage-devel/c/3mCIV9LnP9c/m/lQXLEGKcCQAJ

Naming was discussed during https://wiki.sagemath.org/days111 and a decision made to use the sagemath-... format and in particular sagemath-standard.

CC: @dimpase @jhpalmieri @mmasdeu @videlec @malb @kiwifb @embray @NathanDunfield @slel @orlitzky @fchapoton @vbraun @seblabbe @williamstein @mwageringel @saraedum

Component: build

Keywords: sd111

Author: Matthias Koeppe

Branch/Commit: 7ad4c0e

Reviewer: John Palmieri

Issue created by migration from https://trac.sagemath.org/ticket/30912