fix(parse): honor custom style structlike

[quinnj]

Summary

• forward structlike checks from JSONReadStyle to wrapped custom JSONStyles
• add an issue JSON ignores StructUtils methods for custom JSONStyle for structlike #462 regression covering Base.RefValue{Int} round-tripping through a custom style

Testing

• git diff --check
• focused issue JSON ignores StructUtils methods for custom JSONStyle for structlike #462 repro on Julia 1.12.5
• julia --startup-file=no --project=. -e 'using Pkg; Pkg.test(; coverage=false)'

Fixes #462

[codecov]

Codecov Report

❌ Patch coverage is 50.00000% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 90.20%. Comparing base (19025cc) to head (e269a14).
⚠️ Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
src/parse.jl	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #463      +/-   ##
==========================================
- Coverage   90.26%   90.20%   -0.06%     
==========================================
  Files           7        7              
  Lines        1397     1399       +2     
==========================================
+ Hits         1261     1262       +1     
- Misses        136      137       +1     

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