Update settings for running poseidon

[uzairali19]

This pull request introduces environment-based configuration management and dynamic port allocation to the Poseidon project. The most important changes include adding an .env file for environment variables, refactoring the configuration to load sensitive data from the .env file, and implementing a utility to dynamically allocate free ports for the frontend and backend.

Environment-based configuration:

• mindtrace/ui/mindtrace/ui/poseidon/.env.example: Added a sample .env file with placeholders for environment variables such as MONGO_URI, DB_NAME, SECRET_KEY, GCP_BUCKET_NAME, and GCP_CREDENTIALS_PATH.
• mindtrace/ui/mindtrace/ui/poseidon/.gitignore: Updated .gitignore to exclude the .env file from being tracked in version control.

Refactoring configuration:

• mindtrace/ui/mindtrace/ui/poseidon/poseidon/backend/core/config.py: Refactored the Settings class to load sensitive data (e.g., database URI, secret key, GCP credentials) from the .env file using Pydantic's environment variable support.

Dynamic port allocation:

• mindtrace/ui/mindtrace/ui/poseidon/rxconfig.py: Added a utility function find_free_port to dynamically allocate free ports for the frontend and backend. Integrated this functionality by setting frontend_port and backend_port using environment variables or the utility function.
• mindtrace/ui/mindtrace/ui/poseidon/rxconfig.py: Updated the PoseidonConfig class to include frontend_port and backend_port in the configuration.