Update workers -> Background tasks

With the introduction of self-contained "workers" in the API using the APScheduler, it is a great moment to refactor the "workers" main functions as they are currently designed to run as scripts.

This update will aim to improve the error handling, logging, and standardization of the code to have a better developing experience.

Also, to avoid further concept confusion with the gunicorn "workers", this module will be renamed to bgtasks (Background Tasks).