BHoM_Adapter: refactoring-Pull-Should not have ReadResults() logic in low-level code

This is to open up a discussion started between @alelom, @adecler and @IsakNaslundBh.

## Issue description

Vanilla Pull should be sticking to IBHoMObjects.

This part of the `Pull` method:
https://github.com/BHoM/BHoM_Adapter/blob/12304b8fc904cd4be17101e7f7cd23854a060e4f/BHoM_Adapter/BHoMAdapter.cs#L102-L139

should ideally be moved to more specific parts of the code, as it's relevant only to the structural Adapters.

Start in BHoM_Adapter/BHoMAdapter.cs at the linked Pull method lines 102–139 and inspect the ReadResults() logic there. Trace which parts are relevant only to structural Adapters, then verify that vanilla Pull remains focused on IBHoMObjects and that the structural behavior is handled in more specific Adapter code.

Written by the indexing model from the issue text.