Small CLI cleanups

* yapf changes
* Fix the cformat test
* Make the normpath test work when run from /
* `qmk config`: Mark `--read-only` as arg_only

lib/python/qmk/tests/test_qmk_path.py

@@ -10,4 +10,4 @@ def test_keymap_onekey_pytest():
 
 def test_normpath():
     path = qmk.path.normpath('lib/python')
-    assert path == os.environ['ORIG_CWD'] + '/lib/python'
+    assert path == os.path.join(os.environ['ORIG_CWD'], 'lib/python')