🚀 Enhancement: Account creation on OAuth login should be optional

### 🔖 Enhancement description Account creation on OAuth login should be optional. if a user already exists then login the user else return a error account does not exists. ### 🎤 Pitch In my app i have created a nodejs backend which communicates with appwrite api to login and signup. Upon signup there are some additional steps i want to update in db. So, if a user creates a account with oauth it will break the functionality.. Thats why creating account on oauth login should be optional. ### 👀 Have you spent some time to check if this issue has been raised before? - [X] I checked and didn't find similar issue ### 🏢 Have you read the Code of Conduct? - [X] I have read the [Code of Conduct](https://github.com/appwrite/.github/blob/main/CODE_OF_CONDUCT.md)