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/tests/test_cli_commands.py

@@ -57,9 +57,9 @@ def test_list_keyboards():
 
 
 def test_list_keymaps():
-    result = check_subcommand("list-keymaps", "-kb", "planck/ez")
+    result = check_subcommand("list-keymaps", "-kb", "handwired/onekey/pytest")
     assert result.returncode == 0
-    assert "planck/ez:default" and "planck/ez:drashna" in result.stdout
+    assert "default" and "test" in result.stdout
 
 
 def test_list_keymaps_no_keyboard_found():