feat: event aggregator (#6218)

What:
- Event Aggregator Util
- Preparation for normalizing event in a new format (backward compatible with the current format)
- GQL Schema to joiner config and some Entities configured
- Link modules emmiting events

packages/event-bus-local/src/services/event-bus-local.ts

@@ -1,5 +1,11 @@
 import { MedusaContainer } from "@medusajs/modules-sdk"
-import { EmitData, EventBusTypes, Logger, Subscriber } from "@medusajs/types"
+import {
+  EmitData,
+  EventBusTypes,
+  Logger,
+  Message,
+  Subscriber,
+} from "@medusajs/types"
 import { AbstractEventBusModuleService } from "@medusajs/utils"
 import { EventEmitter } from "events"
 import { ulid } from "ulid"
@@ -37,14 +43,16 @@ export default class LocalEventBusService extends AbstractEventBusModuleService
    */
   async emit<T>(data: EmitData<T>[]): Promise<void>
 
-  async emit<T, TInput extends string | EmitData<T>[] = string>(
+  async emit<T>(data: Message<T>[]): Promise<void>
+
+  async emit<T, TInput extends string | EmitData<T>[] | Message<T>[] = string>(
     eventOrData: TInput,
     data?: T,
     options: Record<string, unknown> = {}
   ): Promise<void> {
     const isBulkEmit = Array.isArray(eventOrData)
 
-    const events: EmitData[] = isBulkEmit
+    const events: EmitData[] | Message<T>[] = isBulkEmit
       ? eventOrData
       : [{ eventName: eventOrData, data }]
 
@@ -61,7 +69,8 @@ export default class LocalEventBusService extends AbstractEventBusModuleService
         continue
       }
 
-      this.eventEmitter_.emit(event.eventName, event.data)
+      const data = (event as EmitData).data ?? (event as Message<T>).body
+      this.eventEmitter_.emit(event.eventName, data)
     }
   }