qmk.path.FileType: fix argument handling (qmk#16693)

* qmk.path.FileType: pass in mode as first argument

* Better solution

* Grammar...

lib/python/qmk/path.py

@@ -70,9 +70,11 @@ def normpath(path):
 
 
 class FileType(argparse.FileType):
-    def __init__(self, encoding='UTF-8'):
+    def __init__(self, *args, **kwargs):
         # Use UTF8 by default for stdin
-        return super().__init__(encoding=encoding)
+        if 'encoding' not in kwargs:
+            kwargs['encoding'] = 'UTF-8'
+        return super().__init__(*args, **kwargs)
 
     def __call__(self, string):
         """normalize and check exists