feat(feature-activation): fix criteria validation

[glevco]

Motivation

Due to the way validations were performed on the Criteria class, some tests were flaky and behaving in unexpected ways. This PR changes the way Criteria attributes are validated to a more robust solution.

Acceptance Criteria

• Implement the ValidatedCriteria class and move all Criteria validation to it
• Implement the Criteria.to_validated() method
• Update FeatureSettings validation to use the new Criteria validation structure

Checklist

• If you are requesting a merge into master, confirm this code is production-ready and can be included in future releases as soon as it gets merged

[codecov]

Codecov Report

Merging #708 (454ca26) into master (779494c) will decrease coverage by 0.02%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #708      +/-   ##
==========================================
- Coverage   84.00%   83.99%   -0.02%     
==========================================
  Files         246      246              
  Lines       20517    20523       +6     
  Branches     2769     2770       +1     
==========================================
+ Hits        17236    17238       +2     
- Misses       2707     2709       +2     
- Partials      574      576       +2     

Impacted Files	Coverage Δ
hathor/feature_activation/model/criteria.py	100.00% <100.00%> (ø)
hathor/feature_activation/settings.py	100.00% <100.00%> (ø)

... and 4 files with indirect coverage changes