src: avoid union type-punning in trace values

[XadillaX]

Replace TraceValueUnion with memcpy-based object representation copying to avoid reading inactive union members. Generalize integral values to support all integral and enum types.

This follows the equivalent V8 fix in CL 1886918.

Refs: https://chromium-review.googlesource.com/c/v8/v8/+/1886918
Fixes: #57033

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.16%. Comparing base (b3fb344) to head (3c837ec).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #65933      +/-   ##
==========================================
- Coverage   90.16%   90.16%   -0.01%     
==========================================
  Files         771      771              
  Lines      265434   265436       +2     
  Branches    50450    50447       -3     
==========================================
- Hits       239332   239322      -10     
- Misses      17045    17064      +19     
+ Partials     9057     9050       -7     

Files with missing lines	Coverage Δ
src/tracing/trace_event_legacy_inl.h	79.50% <100.00%> (+1.17%)	⬆️

... and 27 files with indirect coverage changes

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