Interface + base class for condition module

[GiovanniCanali]

Description

This PR fixes #790

In this PR, the following updates have been introduced:

• condition module:
  • Improved and expanded documentation for clarity and usability
  • Extended test coverage
  • Moved data_manager.py and batch_manager.py to the new data/manager submodule
• data/manager submodule:
  • Introduced a unified interface along with a factory class structure for data-manager related instances
  • Moved each data-manager type to its own file
  • Improved and expanded documentation for clarity and usability
  • Extended test coverage

The core logic underpinning the involved modules has remained unchanged from a user perspective.

Checklist

• Code follows the project’s Code Style Guidelines
• Tests have been added or updated
• Documentation has been updated if necessary
• Pull request is linked to an open issue