Add sample route for /itemsource

- Fix missing item guid not displaying in Module\Itemsource

src/App.php

@@ -1523,6 +1523,8 @@ class App
 	 */
 	private function collectRoutes(RouteCollector $routeCollector)
 	{
+		$routeCollector->addRoute(['GET', 'POST'], '/itemsource[/{guid}]', Module\Itemsource::class);
+
 		Hook::callAll('route_collection', $routeCollector);
 	}
 }

src/Module/Itemsource.php

@@ -37,7 +37,6 @@ class Itemsource extends \Friendica\BaseModule
 
 			$conversation = Model\Conversation::getByItemUri($item['uri']);
 
-			$guid = $item['guid'];
 			$item_id = $item['id'];
 			$item_uri = $item['uri'];
 			$source = $conversation['source'];