User addition functionality

[adityashibu]

This pull request includes significant changes to the backend and frontend of the user management system, focusing on adding new user functionality, modifying existing users, and updating the user interface.

Backend Changes:

• Added new endpoints and functions for user management:
  • add_new_user endpoint in backend/fastAPI.py to add a new user with a given name and password.
  • Functions in backend/users.py to load and save user data, add a new user, and delete a user.

Frontend Changes:

• Enhanced the user interface in frontend/src/app/users/page.jsx:
  • Imported additional components and icons for user management.
  • Added state variables and functions to handle adding new users and displaying error messages.
  • Included a dialog for adding new users and a delete button for existing users. [1] [2]

Database Changes:

• Updated database/users_db.json to reflect new user data:
  • Modified existing user entries and removed some users. [1] [2]

These changes enhance the system's ability to manage users more effectively and improve the user experience on the frontend.