Update database configuration and add new schemas
This pull request introduces changes related to the database configuration and schema additions. It includes the following updates:
- Added database configuration to .env.example
- Connected to the MongoDB database using environment variables for configuration
- Added a new schema called ActivityLog to store activity logs
- Created a Cache schema to define the structure of cache objects in the database
- Added necessary dependencies and test cases
These changes improve the functionality and organization of the codebase, allowing for better database operations and tracking of user actions.