feat(types,module-sdk): setup authentication module skeleton (#5943)

**What**
- add authentication module skeleton

packages/authentication/src/module-definition.ts

@@ -0,0 +1,12 @@
+import { ModuleExports } from "@medusajs/types"
+import { AuthenticationModuleService } from "@services"
+import loadConnection from "./loaders/connection"
+import loadContainer from "./loaders/container"
+
+const service = AuthenticationModuleService
+const loaders = [loadContainer, loadConnection] as any
+
+export const moduleDefinition: ModuleExports = {
+  service,
+  loaders,
+}