Implement structuredClone and tests

[hansl]

This API will be necessary when implementing transfer across contexts. For now, it implements the Window.structuredClone() function correctly and passes the tests I took from its documentation.

[codecov]

Codecov Report

❌ Patch coverage is 72.63158% with 26 lines in your changes missing coverage. Please review.
✅ Project coverage is 50.48%. Comparing base (6ddc2b4) to head (d626093).
⚠️ Report is 491 commits behind head on main.

Files with missing lines	Patch %	Lines
core/engine/src/object/builtins/jstypedarray.rs	30.43%	16 Missing ⚠️
core/runtime/src/clone/mod.rs	86.15%	9 Missing ⚠️
core/macros/src/module.rs	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4366      +/-   ##
==========================================
+ Coverage   47.24%   50.48%   +3.23%     
==========================================
  Files         476      508      +32     
  Lines       46892    50903    +4011     
==========================================
+ Hits        22154    25698    +3544     
- Misses      24738    25205     +467     

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[hansl]

For postMessage, I need a context-free variant of JsValue (including special objects) which would also be useful for this PR, so I'll refactor this PR to include it.