Identify Windows support with tags (#35027)

All packages with explicit Windows support can be found with
`spack list --tags=windows`.

This also removes the documentation which explicitly lists
supported packages on Windows (which is currently out of date and
is now unnecessary with the added tags).

Note that if a package does not appear in this list, it *may*
still build on Windows, but it likely means that no explicit
attempt has been made to support it.

var/spack/repos/builtin/packages/clingo/package.py

@@ -22,7 +22,7 @@ class Clingo(CMakePackage):
     homepage = "https://potassco.org/clingo/"
     url = "https://github.com/potassco/clingo/archive/v5.2.2.tar.gz"
     git = "https://github.com/potassco/clingo.git"
-
+    tags = ["windows"]
     maintainers = ["tgamblin", "alalazo"]
 
     version("master", branch="master", submodules=True)