deps: make VC-WIN config generation deterministic

This change adds a clean target to the VC-WIN* Makefiles, then adjusts
the config generation script to call it before config file generation
as well as after. This prevents files from previous configurations from
causing make to incorrectly assume the files are up to date.

PR-URL: https://github.com/nodejs/node/pull/27543


Reviewed-By: Sam Roberts <vieuxtech@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>