[Merged by Bors] - Fix remaining Set tests

[raskad]

This Pull Request changes the following:

• Add locking for Sets during iteration. We already do this for Maps.
• Properly implement negative zero handling for add, has and delete.
• Refactor some Set functions and add spec comments.

[github-actions]

Test262 conformance changes

Test result	main count	PR count	difference
Total	94,277	94,277	0
Passed	71,071	71,076	+5
Ignored	17,324	17,324	0
Failed	5,882	5,877	-5
Panics	14	14	0
Conformance	75.39%	75.39%	+0.01%

Fixed tests (5):

test/built-ins/Set/valid-values.js [strict mode] (previously Failed)
test/built-ins/Set/valid-values.js (previously Failed)
test/built-ins/Set/prototype/forEach/iterates-values-revisits-after-delete-re-add.js [strict mode] (previously Failed)
test/built-ins/Set/prototype/forEach/iterates-values-revisits-after-delete-re-add.js (previously Failed)
test/built-ins/Set/prototype/forEach/this-strict.js [strict mode] (previously Failed)

[codecov]

Codecov Report

Merging #2725 (b229ad1) into main (9b53859) will decrease coverage by 0.06%.
The diff coverage is 65.51%.

@@            Coverage Diff             @@
##             main    #2725      +/-   ##
==========================================
- Coverage   50.45%   50.40%   -0.06%     
==========================================
  Files         395      393       -2     
  Lines       39810    39870      +60     
==========================================
+ Hits        20085    20095      +10     
- Misses      19725    19775      +50     

Impacted Files	Coverage Δ
boa_engine/src/builtins/map/ordered_map.rs	76.92% <ø> (ø)
boa_engine/src/builtins/set/mod.rs	68.85% <57.35%> (-5.12%)	⬇️
boa_engine/src/builtins/set/ordered_set.rs	69.09% <73.17%> (+4.80%)	⬆️
boa_engine/src/builtins/set/set_iterator.rs	89.58% <100.00%> (ø)
boa_engine/src/object/mod.rs	31.21% <100.00%> (-0.32%)	⬇️
boa_engine/src/value/display.rs	66.41% <100.00%> (ø)

... and 15 files with indirect coverage changes

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[HalidOdat]

Looks good to me! :)

[Razican]

Looks good!

[Razican]

bors r+

[bors]

Pull request successfully merged into main.

Build succeeded:

• Build and Test (macos-latest)
• Build and Test (windows-latest)
• Coverage
• Misc