feat(types,modules-sdk): basic module setup for promotions (#5920)

RESOLVES CORE-1580

packages/promotion/mikro-orm.config.dev.ts

@@ -0,0 +1,8 @@
+import * as entities from "./src/models"
+
+module.exports = {
+  entities: Object.values(entities),
+  schema: "public",
+  clientUrl: "postgres://postgres@localhost/medusa-promotion",
+  type: "postgresql",
+}