feat(gen): support uniqueItems validator

[tdakkota]

Fixes #132

[codecov]

Codecov Report

Patch coverage: 88.88% and no project coverage change.

Comparison is base (42e3aa6) 72.38% compared to head (ba5b4d8) 72.39%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #887   +/-   ##
=======================================
  Coverage   72.38%   72.39%           
=======================================
  Files         190      190           
  Lines       14491    14514   +23     
=======================================
+ Hits        10490    10508   +18     
- Misses       3478     3481    +3     
- Partials      523      525    +2     

Impacted Files	Coverage Δ
gen/schema_gen.go	79.24% <72.72%> (-0.33%)	⬇️
gen/ir/validation.go	76.66% <100.00%> (+0.47%)	⬆️
validate/array.go	100.00% <100.00%> (ø)

... and 1 file with indirect coverage changes

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