Implement Gc::new_cyclic

[jedel1043]

This is just the corresponding replacement for the Rc::new_cyclic method, which showed to be useful while I was trying to improve some patterns in our modules implementation.

[github-actions]

Test262 conformance changes

Test result	main count	PR count	difference
Total	95,574	95,574	0
Passed	75,084	75,084	0
Ignored	19,494	19,494	0
Failed	996	996	0
Panics	0	0	0
Conformance	78.56%	78.56%	0.00%

[codecov]

Codecov Report

Patch coverage: 6.66% and project coverage change: -0.02% ⚠️

Comparison is base (8a78061) 50.31% compared to head (2dc5f78) 50.30%.
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3292      +/-   ##
==========================================
- Coverage   50.31%   50.30%   -0.02%     
==========================================
  Files         436      436              
  Lines       42604    42618      +14     
==========================================
  Hits        21438    21438              
- Misses      21166    21180      +14     

Files Changed	Coverage Δ
boa_gc/src/internals/ephemeron_box.rs	78.08% <0.00%> (-8.29%)	⬇️
boa_gc/src/pointers/gc.rs	54.68% <0.00%> (-4.64%)	⬇️
boa_gc/src/pointers/weak.rs	42.10% <0.00%> (-4.96%)	⬇️
boa_gc/src/pointers/ephemeron.rs	93.10% <100.00%> (ø)

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[HalidOdat]

Looks perfect to me! :)