Integrate with AI interpolator

Problem/Motivation

As discussed here #3446245: Add inputter plugins AI interpolator needs features which AI Prompt module has, so it would be great integrating AI Prompt with AI interpolator.
Integration of these different modules needs to ensure great user experience.

Steps to reproduce

Proposed resolution

Options:

• reference prompt (simplest)
• reference prompt with inline_entity_form (and upgrade everything as ajax instead of separate pages)
• create field storage for aiprompt and have it inline as field (and upgrade everything as ajax) #3446532: Implement aiprompt_field submodule
• organize prompt in a modal
• organize prompt in a sidebar

Remaining tasks

• Determine the best integration path

User interface changes

API changes

Data model changes