Change error architecture to interface

[andrewcurioso]

This PR changes ValidationError to an interface and removes ValidationErrorCollection in favor of more idiomatic Join/Unwrap behavior.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (05d678c) to head (6f68348).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##              main       #52    +/-   ##
==========================================
  Coverage   100.00%   100.00%            
==========================================
  Files           78        78            
  Lines         5299      5126   -173     
==========================================
- Hits          5299      5126   -173     

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