PISHPS-311: added custom event and cart collector for subscriptions

[m-muxfeld-diw]

@BlackScorp can be tested with this patch

Index: src/Subscriber/OrderDeliverySubscriber.php
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
diff --git a/src/Subscriber/OrderDeliverySubscriber.php b/src/Subscriber/OrderDeliverySubscriber.php
--- a/src/Subscriber/OrderDeliverySubscriber.php    (revision 9e1fa93e083290440433789acf788843ef0cf41a)
+++ b/src/Subscriber/OrderDeliverySubscriber.php    (date 1723028422423)
@@ -3,6 +3,7 @@
 namespace Kiener\MolliePayments\Subscriber;

 use Kiener\MolliePayments\Components\ShipmentManager\ShipmentManager;
+use Kiener\MolliePayments\Event\MollieSubscriptionCartItemAddedEvent;
 use Kiener\MolliePayments\Repository\OrderTransaction\OrderTransactionRepositoryInterface;
 use Kiener\MolliePayments\Service\OrderService;
 use Kiener\MolliePayments\Service\SettingsService;
@@ -64,6 +65,7 @@
     {
         return [
             'state_machine.order_delivery.state_changed' => 'onOrderDeliveryChanged',
+            MollieSubscriptionCartItemAddedEvent::class => 'test'
         ];
     }

@@ -123,4 +125,9 @@
             return;
         }
     }
+
+    public function test(MollieSubscriptionCartItemAddedEvent $event)
+    {
+        $a = 1;
+    }
 }