test: add windows and C++ coverage

Collect Windows and C++ coverage. Configure codecov so that
comments are more concise and are only left when coverage
varies.

PR-URL: https://github.com/nodejs/node/pull/35670
Fixes: https://github.com/nodejs/node/issues/35696
Refs: https://github.com/nodejs/node/pull/35653
Refs: https://github.com/nodejs/node/issues/35646
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Richard Lau <rlau@redhat.com>
Reviewed-By: Jiawen Geng <technicalcute@gmail.com>
Reviewed-By: Michael Dawson <midawson@redhat.com>

codecov.yml

@@ -0,0 +1,10 @@
+comment:
+  # Only show diff and files changed:
+  layout: "diff, files"
+  # Don't post if no changes in coverage:
+  require_changes: true
+
+codecov:
+  notify:
+    # Wait for all coverage builds:
+    after_n_builds: 2