Code cleanup, use pathlib, use pytest keyboard

Clean up checks and logics that are unnecessary due to MILC updates.
Use pathlib instead of os.path for readability.
Use the 'pytest' keyboard for the tests.
Add community layout for 'handwired/onekey/pytest' so we can test
community layouts.

lib/python/qmk/path.py

@@ -33,16 +33,3 @@ def normpath(path):
         return os.path.normpath(path)
 
     return os.path.normpath(os.path.join(os.environ['ORIG_CWD'], path))
-
-
-def file_lines(filename):
-    """ Return a files content, line by line
-
-    Args:
-        filename: path to the file
-
-    Returns:
-        an list, in which each item is a line of the file
-    """
-    with open(filename, "r") as fd:
-        return fd.readlines()