feat: v2 - add worker mode (#6739)

**What**
- Adds support for starting a Medusa process with a worker mode.
- The worker modes supported are "shared", "worker", "server"
- In "worker" mode, API routes are not registered and modules that need to run workers (e.g., event bus redis) can use the flag to conditionally start workers.
- In "server" mode, API routes are registered and workers are not started.
- In "shared" mode, API routes are registered and workers are started. This is great for development.

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

@@ -42,11 +42,14 @@ export default class RedisEventBusService extends AbstractEventBusModuleService
     })
 
     // Register our worker to handle emit calls
-    new Worker(moduleOptions.queueName ?? "events-queue", this.worker_, {
-      prefix: `${this.constructor.name}`,
-      ...(moduleOptions.workerOptions ?? {}),
-      connection: eventBusRedisConnection,
-    })
+    const shouldStartWorker = moduleDeclaration.worker_mode !== "server"
+    if (shouldStartWorker) {
+      new Worker(moduleOptions.queueName ?? "events-queue", this.worker_, {
+        prefix: `${this.constructor.name}`,
+        ...(moduleOptions.workerOptions ?? {}),
+        connection: eventBusRedisConnection,
+      })
+    }
   }
 
   /**