Align our subprocess usage with current best practices. (#12940)

* Align our subprocess usage with current best practices.

* remove unused import

* Apply suggestions from code review

Co-authored-by: Ryan <fauxpark@gmail.com>

* fix the cpp invocation for older python

* allow for unprompted installation

* make sure qmk new-keyboard works on windows

Co-authored-by: Ryan <fauxpark@gmail.com>

lib/python/qmk/cli/new/keyboard.py

@@ -8,4 +8,4 @@ def new_keyboard(cli):
     """Creates a new keyboard
     """
     # TODO: replace this bodge to the existing script
-    cli.run(['util/new_keyboard.sh'], capture_output=False)
+    cli.run(['util/new_keyboard.sh'], stdin=None, capture_output=False)