Support for overrides.json5 (#179)

This adds support for the json5 format for setting overrides.
It will look for overrides.json then overrides.json5. Both can
be in json5 (of which JSON is a subset)

Fixes: jupyterlab/jupyterlab#10010

Co-authored-by: Marc Udoff <[email protected]>

Author: mlucool

jupyterlab_server/settings_handler.py

@@ -259,10 +259,12 @@ def _get_overrides(app_settings_dir):
     """Get overrides settings from `app_settings_dir`."""
     overrides, error = {}, ""
     overrides_path = os.path.join(app_settings_dir, 'overrides.json')
+    if not os.path.exists(overrides_path):
+        overrides_path = os.path.join(app_settings_dir, 'overrides.json5')
     if os.path.exists(overrides_path):
         with open(overrides_path, encoding='utf-8') as fid:
             try:
-                overrides = json.load(fid)
+                overrides = json5.load(fid)
             except Exception as e:
                 error = e
     # Allow `default_settings_overrides.json` files in <jupyter_config>/labconfig dirs