Make foreign NotificationGroupItems aware of their section

This caused notifications on mobile to show notifications for
both alert|message, as the type was always "all".

Bug: T130801
Change-Id: Ice245eb407ca360d8e882c0ba48cb7b3e0ecb851

includes/api/ApiEchoNotifications.php

@@ -313,6 +313,7 @@ class ApiEchoNotifications extends ApiQueryBase {
 		$output = EchoDataOutputFormatter::formatOutput( $notif, $format, $user, $this->getLanguage() );
 
 		// Add cross-wiki-specific data
+		$output['section'] = $section;
 		$output['count'] = $count;
 		$output['sources'] = $foreignNotifications->getApiEndpoints( $wikis );
 		// Add timestamp information

modules/viewmodel/mw.echo.dm.NotificationsModel.js

@@ -532,6 +532,7 @@
 									// For bundles that are not foreign (like regular
 									// bundles of notifications) this flag should be false
 									foreign: true,
+									type: notifData.section,
 									count: notifData.count
 								} )
 							);