Implement the array-grouping proposal

[jedel1043]

Two simple additions to the builtins: Object.groupBy and Map.groupBy.

[github-actions]

Test262 conformance changes

Test result	main count	PR count	difference
Total	95,609	95,609	0
Passed	75,926	75,978	+52
Ignored	18,924	18,872	-52
Failed	759	759	0
Panics	0	0	0
Conformance	79.41%	79.47%	+0.05%

Fixed tests (52):

test/built-ins/Map/groupBy/groupLength.js [strict mode] (previously Ignored)
test/built-ins/Map/groupBy/groupLength.js (previously Ignored)
test/built-ins/Map/groupBy/length.js [strict mode] (previously Ignored)
test/built-ins/Map/groupBy/length.js (previously Ignored)
test/built-ins/Map/groupBy/negativeZero.js [strict mode] (previously Ignored)
test/built-ins/Map/groupBy/negativeZero.js (previously Ignored)
test/built-ins/Map/groupBy/emptyList.js [strict mode] (previously Ignored)
test/built-ins/Map/groupBy/emptyList.js (previously Ignored)
test/built-ins/Map/groupBy/iterator-next-throws.js [strict mode] (previously Ignored)
test/built-ins/Map/groupBy/iterator-next-throws.js (previously Ignored)
test/built-ins/Map/groupBy/callback-throws.js [strict mode] (previously Ignored)
test/built-ins/Map/groupBy/callback-throws.js (previously Ignored)
test/built-ins/Map/groupBy/map-instance.js [strict mode] (previously Ignored)
test/built-ins/Map/groupBy/map-instance.js (previously Ignored)
test/built-ins/Map/groupBy/callback-arg.js [strict mode] (previously Ignored)
test/built-ins/Map/groupBy/callback-arg.js (previously Ignored)
test/built-ins/Map/groupBy/invalid-iterable.js [strict mode] (previously Ignored)
test/built-ins/Map/groupBy/invalid-iterable.js (previously Ignored)
test/built-ins/Map/groupBy/invalid-callback.js [strict mode] (previously Ignored)
test/built-ins/Map/groupBy/invalid-callback.js (previously Ignored)
test/built-ins/Map/groupBy/evenOdd.js [strict mode] (previously Ignored)
test/built-ins/Map/groupBy/evenOdd.js (previously Ignored)
test/built-ins/Map/groupBy/name.js [strict mode] (previously Ignored)
test/built-ins/Map/groupBy/name.js (previously Ignored)
test/built-ins/Map/groupBy/toPropertyKey.js [strict mode] (previously Ignored)
test/built-ins/Map/groupBy/toPropertyKey.js (previously Ignored)
test/built-ins/Object/groupBy/groupLength.js [strict mode] (previously Ignored)
test/built-ins/Object/groupBy/groupLength.js (previously Ignored)
test/built-ins/Object/groupBy/length.js [strict mode] (previously Ignored)
test/built-ins/Object/groupBy/length.js (previously Ignored)
test/built-ins/Object/groupBy/emptyList.js [strict mode] (previously Ignored)
test/built-ins/Object/groupBy/emptyList.js (previously Ignored)
test/built-ins/Object/groupBy/iterator-next-throws.js [strict mode] (previously Ignored)
test/built-ins/Object/groupBy/iterator-next-throws.js (previously Ignored)
test/built-ins/Object/groupBy/callback-throws.js [strict mode] (previously Ignored)
test/built-ins/Object/groupBy/callback-throws.js (previously Ignored)
test/built-ins/Object/groupBy/callback-arg.js [strict mode] (previously Ignored)
test/built-ins/Object/groupBy/callback-arg.js (previously Ignored)
test/built-ins/Object/groupBy/invalid-iterable.js [strict mode] (previously Ignored)
test/built-ins/Object/groupBy/invalid-iterable.js (previously Ignored)
test/built-ins/Object/groupBy/null-prototype.js [strict mode] (previously Ignored)
test/built-ins/Object/groupBy/null-prototype.js (previously Ignored)
test/built-ins/Object/groupBy/invalid-callback.js [strict mode] (previously Ignored)
test/built-ins/Object/groupBy/invalid-callback.js (previously Ignored)
test/built-ins/Object/groupBy/evenOdd.js [strict mode] (previously Ignored)
test/built-ins/Object/groupBy/evenOdd.js (previously Ignored)
test/built-ins/Object/groupBy/name.js [strict mode] (previously Ignored)
test/built-ins/Object/groupBy/name.js (previously Ignored)
test/built-ins/Object/groupBy/invalid-property-key.js [strict mode] (previously Ignored)
test/built-ins/Object/groupBy/invalid-property-key.js (previously Ignored)
test/built-ins/Object/groupBy/toPropertyKey.js [strict mode] (previously Ignored)
test/built-ins/Object/groupBy/toPropertyKey.js (previously Ignored)

[codecov]

Codecov Report

Attention: 61 lines in your changes are missing coverage. Please review.

Comparison is base (808a08a) 45.45% compared to head (973e0b0) 45.40%.
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3420      +/-   ##
==========================================
- Coverage   45.45%   45.40%   -0.06%     
==========================================
  Files         483      483              
  Lines       49743    49808      +65     
==========================================
+ Hits        22613    22615       +2     
- Misses      27130    27193      +63     

Files	Coverage Δ
boa_engine/src/builtins/object/mod.rs	59.29% <12.50%> (-3.75%)	⬇️
boa_engine/src/builtins/map/mod.rs	65.65% <8.33%> (-12.88%)	⬇️

... and 2 files with indirect coverage changes

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[Razican]

Looks great! Thanks!