[2.0.0-beta4] Evolution of DeriableContexts : refactor code with source plugin manager, add several contexts in derivation, and better support prop types

ready for review

this issue has
- the original code from 🐛 [2.0.0-alpha2] Field Formatters: Re-enable the source plugin entity reference Active
- a new improvement in derivable contexts plugin listing, especially applicable to "Data from a field". Indeed, that source won't propose anymore inapplicable contexts. Derivable contexts shown in the select list are guaranteed to propose at least one selectable source in their prop/slot form.

this issue has the foundations for another important issue 🐛 [2.0.0-alpha2] Field Formatters: Re-enable the source plugin entity reference Active , introducing new derivable contexts for entity reference fields.

ok by christian multiple reviews, let's merge this

Automatically closed - issue fixed for 2 weeks with no activity.