Feature/stk 3020 upgrade haystack 4

[garethj2]

A long overdue upgrade of haystack core to make it up to date with the latest haystack standard.

Please see these proposals that have now been implemented (except https://project-haystack.org/forum/topic/937)...

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.
• Reworked relationship haystack filter query.
• Using latest version of Rust with all clippy recommendations implemented. @hecsalazarf please take a look at these changes. It's been a while since I've coded in Rust and I've lost a little confidence when it comes to use of life times.
• Detect haystack filter parser fragments. It seems like not all of a filter was being parsed properly and some error cases where being missed.

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.

[rracariu]

LGTM. Hector's comments look sensible too.
It might require a cargo update to get all the deps to latest.