feat(core): errors validation presenter json migration to core

[Matii96]

PR Checklist

Please check if your PR fulfills the following requirements:

• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

What is the current behavior?

Json errors validation presenter is provided by standalone package

What is the new behavior?

Json presenter moved to core package - no separate package installation required.

@unifig/validation-presenter-json package is deprecated but backwards compatible.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.06%. Comparing base (5aefedb) to head (e8cc159).
Report is 4 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #20      +/-   ##
==========================================
+ Coverage   97.03%   97.06%   +0.02%     
==========================================
  Files          36       38       +2     
  Lines         405      409       +4     
  Branches       72       72              
==========================================
+ Hits          393      397       +4     
  Misses         12       12              

Flag	Coverage Δ
unittests	97.06% <100.00%> (+0.02%)	⬆️

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