feat: add when constraint

[imranbarbhuiya]

Not ready for review yet. I haven't even started. Just fixed the typings and added a test

I'll finish it after my exams. In the meantime, if anyone else is interested then u can create a pr and I'll close this one

The code is ready for review.

TODO:

• Add more tests.

[codecov-commenter]

Codecov Report

Base: 99.35% // Head: 99.36% // Increases project coverage by +0.01% 🎉

Coverage data is based on head (e2ebb91) compared to base (aae857c).
Patch coverage: 100.00% of modified lines in pull request are covered.

❗ Current head e2ebb91 differs from pull request most recent head 74256fb. Consider uploading reports for the commit 74256fb to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #223      +/-   ##
==========================================
+ Coverage   99.35%   99.36%   +0.01%     
==========================================
  Files          57       58       +1     
  Lines        3400     3470      +70     
  Branches      811      828      +17     
==========================================
+ Hits         3378     3448      +70     
  Misses         13       13              
  Partials        9        9              

Impacted Files	Coverage Δ
src/constraints/ObjectConstrains.ts	100.00% <100.00%> (ø)
src/constraints/util/isUnique.ts	100.00% <100.00%> (ø)
src/lib/errors/BaseConstraintError.ts	100.00% <100.00%> (ø)
src/validators/BaseValidator.ts	100.00% <100.00%> (ø)
src/validators/ObjectValidator.ts	97.89% <100.00%> (+0.02%)	⬆️

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