Implement Iterator.prototype.includes proposal

[nekevss]

This PR implements the new Stage 2.7 Iterator includes proposal and adds some tests for it as well.

It's worth noting that the current tests don't take advantage of generator functions because our iterator helpers don't appear to work correctly with them, which we should probably look into. In the meantime, an arrow function returning an iterator was used.

I left the clamping of the skippedElements value to the range of i64, which I believe should be sufficient since it is beyond the MAX_SAFE_INTEGER.

Also worth noting, there's not test262 tests yet AFAIK, so no unflagging is needed currently.

CC: @michaelficarra for the visibility since we were talking about this just the other day

[github-actions]

Test262 conformance changes

Test result	main count	PR count	difference
Total	52,963	52,963	0
Passed	50,732	50,732	0
Ignored	1,426	1,426	0
Failed	805	805	0
Panics	0	0	0
Conformance	95.79%	95.79%	0.00%

Tested main commit: 8fcbfcbb8b9e70fe878d28376a6496eaa57a70d7
Tested PR commit: 7bf4089cf1a071ebe686d46a9bf625040c239aa6
Compare commits: 8fcbfcb...7bf4089

[codecov]

Codecov Report

❌ Patch coverage is 96.00000% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 59.73%. Comparing base (6ddc2b4) to head (7bf4089).
⚠️ Report is 918 commits behind head on main.

Files with missing lines	Patch %	Lines
...engine/src/builtins/iterable/iterator_prototype.rs	96.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #5227       +/-   ##
===========================================
+ Coverage   47.24%   59.73%   +12.48%     
===========================================
  Files         476      589      +113     
  Lines       46892    63431    +16539     
===========================================
+ Hits        22154    37889    +15735     
- Misses      24738    25542      +804     

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