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/types/src/common/config-module.ts

@@ -485,6 +485,25 @@ export type ProjectConfigOptions = {
    * ```
    */
   jobs_batch_size?: number
+
+  /**
+   * Configure the application's worker mode. The default value is `shared`.
+   * - Use `shared` if you want to run the application in a single process.
+   * - Use `worker` if you want to run the a worker process only.
+   * - Use `server` if you want to run the application server only.
+   *
+   * @example
+   * ```js title="medusa-config.js"
+   * module.exports = {
+   *   projectConfig: {
+   *     worker_mode: "shared"
+   *     // ...
+   *   },
+   *   // ...
+   * }
+   * ```
+   */
+  worker_mode?: "shared" | "worker" | "server"
 }
 
 /**

packages/types/src/modules-sdk/index.ts

@@ -48,6 +48,7 @@ export type InternalModuleDeclaration = {
    * If the module is the main module for the key when multiple ones are registered
    */
   main?: boolean
+  worker_mode?: "shared" | "worker" | "server"
 }
 
 export type ExternalModuleDeclaration = {