add: refactorisation of the detail logic, handled now in sub-functions

[alecorvec]

Describe your changes

Change the way the details of a food are selected, and how the user choices are handled in storage and rendering.

Issue ticket number and link

Closes #65

Checklist before requesting a review

• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• I have performed a self-review of my code
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Documentation has been updated as required
  If a single item in this checklist is not checked, the pull request cannot be accepted