Adapt Arx to new jbk API.
This is mainly a simplification of the API made in jubako. (jubako!26 (merged))
We follow this and simplify a bit our code :
- No more resolver (properties know how to resolve themselves)
- No need to store a value_storage in the builder (see previous point)
- No more schema (use a free function to create the builder from a layout)
- no more finder. We now directly use the index/range to know where we search/get_entry and the builder to know how we construct entries.