Implement Initial Backend and User Storage

### Description

This ticket is for implementing the initial backend and user storage for the Minesweeper game. The following tasks should be completed:

- Create a backend using Python and Flask.
- Use SQL Alchemy as the Object-Relational Mapping (ORM) tool for database management.
- Use PostGres SQL as the database engine.
- Implement OAuth for user authentication and authorization.
- Create an endpoint that saves user data to the database.

### Acceptance Criteria

- The backend should be created using Python and Flask, with SQL Alchemy as the ORM tool and PostGres SQL as the database engine.
- OAuth should be implemented for user authentication and authorization.
- The endpoint for saving user data should be created and should function properly.
- The user data should include at least a unique identifier and any additional information required for user authentication and authorization.

### Out of Scope

- Creating an endpoint that sends game status is out of scope for this ticket.
- If game status is implemented, it should only be sent for finished games and should include relevant game information.

### Additional Notes

- The user data should be securely stored in the database to protect user privacy and prevent unauthorized access.
- The endpoint for saving user data should include appropriate error handling to prevent data corruption and ensure data integrity.
- The backend should be scalable and capable of handling a large number of user requests simultaneously.
- All code should be thoroughly tested to ensure that it is stable and works as expected.

Once this ticket is completed, the backend and user storage will be fully functional and ready for integration with the Minesweeper game.