tools/mpremote: Locate config.py location across different host OSes.

Use `platformdirs.user_config_dir()` (see
https://platformdirs.readthedocs.io/en/latest/api.html#user-config-directory)
to provide portability across many different OSes and configuration styles.

Signed-off-by: Jos Verlinde <Jos_Verlinde@hotmail.com>

tools/mpremote/mpremote/main.py

@@ -22,6 +22,8 @@ import os, sys, time
 from collections.abc import Mapping
 from textwrap import dedent
 
+import platformdirs
+
 from .commands import (
     CommandError,
     do_connect,
@@ -439,13 +441,7 @@ def load_user_config():
     config.commands = {}
 
     # Get config file name.
-    path = os.getenv("XDG_CONFIG_HOME")
-    if path is None:
-        path = os.getenv("HOME")
-        if path is None:
-            return config
-        path = os.path.join(path, ".config")
-    path = os.path.join(path, _PROG)
+    path = platformdirs.user_config_dir(appname=_PROG, appauthor=False)
     config_file = os.path.join(path, "config.py")
 
     # Check if config file exists.
@@ -457,6 +453,9 @@ def load_user_config():
         config_data = f.read()
     prev_cwd = os.getcwd()
     os.chdir(path)
+    # Pass in the config path so that the config file can use it.
+    config.__dict__["config_path"] = path
+    config.__dict__["__file__"] = config_file
     exec(config_data, config.__dict__)
     os.chdir(prev_cwd)