Fix unsoundness in JsValueStore by replacing unsafe raw pointer mutation of Arc with safe OnceLock

[mansiverma897993]

This Pull Request fixes/closes #5392.

It changes the following:

• Fix unsoundness in JsValueStore by replacing unsafe raw pointer mutation of Arc with safe OnceLock

[github-actions]

Test262 conformance changes

Test result	main count	PR count	difference
Total	53,125	53,125	0
Passed	51,072	51,072	0
Ignored	1,482	1,482	0
Failed	571	571	0
Panics	0	0	0
Conformance	96.14%	96.14%	0.00%

Tested main commit: 7ce9cae84ac9bf54fe528bb05b997ac24af808a4
Tested PR commit: 15efcccd5b510d1661538c3f6e7a8971f0e16f63
Compare commits: 7ce9cae...15efccc

[codecov]

Codecov Report

❌ Patch coverage is 46.87500% with 17 lines in your changes missing coverage. Please review.
✅ Project coverage is 60.22%. Comparing base (6ddc2b4) to head (15efccc).
⚠️ Report is 982 commits behind head on main.

Files with missing lines	Patch %	Lines
core/macros/src/lib.rs	0.00%	17 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #5408       +/-   ##
===========================================
+ Coverage   47.24%   60.22%   +12.98%     
===========================================
  Files         476      567       +91     
  Lines       46892    63158    +16266     
===========================================
+ Hits        22154    38040    +15886     
- Misses      24738    25118      +380     

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[hansl]

Why is the macro change part of this PR? Feels like it should be its own PR, can you split them?