feat(auth): Add error handling for authentication and validation errors
feat(auth): Implement default role assignment for new users in Google OAuth flow
feat(utils): Introduce CSRF token generation and validation utilities
fix(dependencies): Update Cargo.toml to include base64 and sha2 dependencies
- Added Google OAuth controller and service to handle authentication via Google.
- Introduced DTOs for Google user and token responses.
- Updated AuthService and UsersService traits to support new Google OAuth functionality.
- Implemented logic to create a new user if they do not exist in the system after Google authentication.
- Enhanced existing user retrieval and JWT generation upon successful login.
- Added tests for Google OAuth flow, including login redirection and callback handling for both new and existing users.
- Updated environment configuration to include Google OAuth credentials.