Feat(medusa, user, core-flows): User creation with invites (#6413)

**What**
- add accept invite endpoint 

**Invite accept flow**
- authenticate using the auth endpoint to create and auth-user
- invoke accept endpoint with token and info to create user

packages/user/package.json

@@ -56,6 +56,7 @@
     "@mikro-orm/postgresql": "5.9.7",
     "awilix": "^8.0.0",
     "dotenv": "16.3.1",
+    "jsonwebtoken": "^9.0.2",
     "knex": "2.4.2"
   }
 }