feat: Add support for authentication to the sdk, and plug it in the admin (#7349)

* feat: Add support for authentication to the sdk, and plug it in the admin

* fix: await fetch before returning in sdk

packages/core/js-sdk/src/index.ts

@@ -1,17 +1,22 @@
 import { Admin } from "./admin"
+import { Auth } from "./auth"
 import { Client } from "./client"
 import { Store } from "./store"
 import { Config } from "./types"
 
 class Medusa {
   public client: Client
+
   public admin: Admin
   public store: Store
+  public auth: Auth
 
   constructor(config: Config) {
     this.client = new Client(config)
+
     this.admin = new Admin(this.client)
     this.store = new Store(this.client)
+    this.auth = new Auth(this.client, config)
   }
 }