Updated the database models with new tables

[Armolas]

Addition:

• Added tables for subscriptions, waitlist_users, blogs and jobs
• created migrations for the added tables
• Added is_active column to users table
• created password_auth file in utils for hashing and validating passwords
• created a JsonResponseDict class to enforce the recommended response convention
• created a BaseModel to add the following methods to the models:

• to_dict(): returns a dictionary representation of the model instance
• get_all(): returns all objects of the model stored in the database
• get_by_id(id: str): returns a single instance of the model whose id was passed as argument