feat(region): Add admin region get + list endpoints (#6322)

**What**
Add `GET /admin/regions`
Add `GET /admin/regions/:id`

Blocked by #6320 

Co-authored-by: Adrien de Peretti <25098370+adrien2p@users.noreply.github.com>

packages/modules-sdk/src/loaders/utils/load-internal.ts

@@ -16,7 +16,8 @@ import { asFunction, asValue } from "awilix"
 export async function loadInternalModule(
   container: MedusaContainer,
   resolution: ModuleResolution,
-  logger: Logger
+  logger: Logger,
+  migrationOnly?: boolean
 ): Promise<{ error?: Error } | void> {
   const registrationName = resolution.definition.registrationName
 
@@ -64,6 +65,17 @@ export async function loadInternalModule(
     }
   }
 
+  if (migrationOnly) {
+    // Partially loaded module, only register the service __joinerConfig function to be able to resolve it later
+    const moduleService = {
+      __joinerConfig: loadedModule.service.prototype.__joinerConfig,
+    }
+    container.register({
+      [registrationName]: asValue(moduleService),
+    })
+    return
+  }
+
   const localContainer = createMedusaContainer()
 
   const dependencies = resolution?.dependencies ?? []