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.

.changeset/ninety-months-allow.md

@@ -0,0 +1,8 @@
+---
+"@medusajs/medusa": patch
+"@medusajs/event-bus-redis": patch
+"@medusajs/modules-sdk": patch
+"@medusajs/types": patch
+---
+
+feat: v2 - add worker mode