Change test evaluation

[johnynek]

related to #1180

Just using parallelism doesn't work because MatchlessToValue uses mutable state and it seems that threading breaks.

Considering how to make that work when values can be evaluated in parallel requires some thought. Probably using Eval at all won't work, and we will need something smarter.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 83.33333% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 91.55%. Comparing base (04a0e87) to head (4b541bc).
Report is 19 commits behind head on main.

Files	Patch %	Lines
...i/src/main/scala/org/bykn/bosatsu/PathModule.scala	75.00%	1 Missing ⚠️

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Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1187      +/-   ##
==========================================
+ Coverage   91.32%   91.55%   +0.23%     
==========================================
  Files          96       96              
  Lines       11846    12014     +168     
  Branches     2675     2766      +91     
==========================================
+ Hits        10818    11000     +182     
+ Misses       1028     1014      -14     

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