win: block running on EOL Windows versions

Windows 7 and Windows Server 2008 R2 EOL was January 14, 2020.
Windows 8 EOL was January 12, 2016.

Windows 2012 (not R2) is still supported and allowed to run. This
clarifies that support is experimental.

PR-URL: https://github.com/nodejs/node/pull/31954


Reviewed-By: Rod Vagg <rod@vagg.org>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: David Carlier <devnexen@gmail.com>
Reviewed-By: Franziska Hinkelmann <franziska.hinkelmann@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>