Agnostic_baker: Refactor code and improve documentation

What

Parent MR: !17410 (merged)

Major refactoring and a lot of new documentation for most modules in the Lib_agnostic_baker to ease the understanding and debugging of the module.

Why

How

Manually testing the MR

CI green + tezt-cloud scenarios

Checklist

• Document the interface of any function added or modified (see the coding guidelines)
• Document any change to the user interface, including configuration parameters (see node configuration)
• Provide automatic testing (see the testing guide).
• For new features and bug fixes, add an item in the appropriate changelog (docs/protocols/alpha.rst for the protocol and the environment, CHANGES.rst at the root of the repository for everything else).
• Select suitable reviewers using the Reviewers field below.
• Select as Assignee the next person who should take action on that MR