feat(product, types, modules-sdk): added event bus events for products (#4654)

what:

- adds an eventbus dependency to product module.
- emits events on product, category and collection CUD

RESOLVES CORE-1450

packages/product/integration-tests/__fixtures__/event-bus/index.ts

@@ -0,0 +1,36 @@
+import {
+  EmitData,
+  EventBusTypes,
+  Subscriber,
+  IEventBusModuleService
+} from "@medusajs/types"
+
+export class EventBusService implements IEventBusModuleService {
+  async emit<T>(
+    eventName: string,
+    data: T,
+    options: Record<string, unknown>
+  ): Promise<void>
+  async emit<T>(data: EventBusTypes.EmitData<T>[]): Promise<void>
+  async emit<T, TInput extends string | EventBusTypes.EmitData<T>[] = string>(
+    eventOrData: TInput,
+    data?: T,
+    options: Record<string, unknown> = {}
+  ): Promise<void> {}
+
+  subscribe(event: string | symbol, subscriber: Subscriber): this {
+    return this
+  }
+
+  unsubscribe(
+    event: string | symbol,
+    subscriber: Subscriber,
+    context?: EventBusTypes.SubscriberContext
+  ): this {
+    return this
+  }
+
+  withTransaction() {
+
+  }
+}