fix(centurion): route sub-device notifications via sub_inverse in get_feature

Bridge MessageEvents arrive with sub_feat_idx + 0x100 as the notification
sub_id. get_feature() only checked self.inverse (parent features), so sub-
device feature notifications (including CENTURION_BATTERY_SOC charging
changes) were silently dropped with 'invalid feature index'.

Check sub_inverse at index - 0x100 for any index >= 0x100 so spontaneous
notifications from the headset (e.g. charging status change) are correctly
dispatched to the feature notification handler.

lib/logitech_receiver/hidpp20.py

@@ -301,6 +301,8 @@ class FeaturesArray(dict):
         feature = self.inverse.get(index)
         if feature is not None:
             return feature
+        if index >= 0x100:
+            return self.sub_inverse.get(index - 0x100)
         elif self._check():
             feature = self.inverse.get(index)
             if feature is not None: