Added Override Notification Option to Weather Module (#3178)

Fixes #3126 

Added the option `allowOverrideNotification` to `weather.js`. This
allows the module to receive the `CURRENT_WEATHER_OVERRIDE`
notification. The expected payload for this notification is a
full/partial `weatherObject` that is used to supplement/replace the
existing `weatherObject` returned by whichever weather provider is in
use.

No visual changes.

First time contributing - let me know if I've missed something
🙂

---------

Co-authored-by: veeck <michael.veeck@nebenan.de>

modules/default/weather/weatherprovider.js

@@ -1,4 +1,4 @@
-/* global Class, performWebRequest */
+/* global Class, performWebRequest, OverrideWrapper */
 
 /* MagicMirror²
  * Module: Weather
@@ -164,5 +164,9 @@ WeatherProvider.initialize = function (providerIdentifier, delegate) {
 		provider.providerName = pi;
 	}
 
+	if (config.allowOverrideNotification) {
+		return new OverrideWrapper(provider);
+	}
+
 	return provider;
 };