1 implement emailpassword auth

[Anish-Chanda]

Add Email password auth method with refresh tokens and sqlite3 default db support. Only supporting for argon2 hashing for now.

Copilot summary:

Authentication Service Implementation:

• authS/authS.go: Added the AuthService struct and methods for handling email-password signup (EmailSignup), login (EmailLogin), and token refresh (HandleRefresh). This includes request validation, password hashing, token generation, and database interactions.

Configuration Setup:

• config/config.go: Defined the Config struct to hold configuration settings such as JWT secrets, token TTLs, database configuration, and password hashing settings. Added a DefaultConfig function to provide default values.

Database Interface and Implementation:

• db/interface.go: Created the Database interface with methods for checking email existence, managing users, and handling refresh tokens.
• db/sqlite3/sqlite3.go: Implemented the Database interface for SQLite3, including methods for creating users, storing refresh tokens, and checking token revocation.

Utility Functions:

• internal/utils/jwt.go: Added utility functions for generating access and refresh tokens using JWT.
• internal/utils/password.go: Implemented password hashing and verification using Argon2 algorithm.
• internal/utils/utils.go: Added utility functions for validating email and password, and generating unique IDs.

Example Application:

• example/main.go: Created an example application to demonstrate the usage of the AuthService, including routes for signup, login, and token refresh.

These changes collectively establish a robust foundation for an authentication system with secure password handling and token-based session management.