core: use ConstraintContext for inference

[superlopuh]

In a way, both constraint verification and inference are a matching of a query with data, where we come up with assignments for the variables, and bail if a unique assignment is not found, so it makes sense to me to use the same data structure to represent variable assignment in both cases.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.17%. Comparing base (30248fd) to head (d64a5de).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4001   +/-   ##
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  Coverage   90.17%   90.17%           
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  Files         458      458           
  Lines       58312    58304    -8     
  Branches     5694     5694           
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- Hits        52580    52573    -7     
+ Misses       4340     4339    -1     
  Partials     1392     1392           

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