feat: restructure events payload (#8143)

* refactor: restructure events payload

Breaking change: This PR changes the event payload accepted by the event
listeners

* refactor: fix failing tests and implement feedback

* add integration tests

* fix timeout

---------

Co-authored-by: Adrien de Peretti <adrien.deperetti@gmail.com>

integration-tests/modules/__tests__/notification/admin/notification.spec.ts

@@ -173,7 +173,7 @@ medusaIntegrationTestRunner({
           const logSpy = jest.spyOn(logger, "info")
 
           await eventBus.emit({
-            eventName: "order.created",
+            name: "order.created",
             data: {
               order: {
                 id: "1234",