Update to latest haystack 4 + performance increases

This proposal has these sub-proposals that have now been implemented...

935: simplify how choices work for the common case to so that they work like all other tags
936: redesign how choices work for the complicated specialization use case via a new design pattern using the of tag
938: finalize the question mark inference operator in filter syntax
939: remove the equipFunction taxonomy until we learn more

Please note this proposal has not been implemented as the changes haven't yet made it into the main haystack-defs repo...

937: redesign ref of (domain/referent of the relationship) to use filters and eliminate the fluid-xxx def explosion

Overall the main biggest changes are...

• Reworked choices (minor).
• Refactor how defs are used in the automated tests. Switched from using hard coded files. This will make it easier for future changes to defs.
• Reworked relationship haystack filter query.
• Removed implied tags support. It was an experiment and no-one uses it.
• Please note, when we release this change, I'll make it a new major version since it relies on a newer version of haystack defs.
• Performance improvements for working with JSON data.