src: skip duplicate UTF-8 validation in TextDecoder fatal path

[mertcanaltin]

In TextDecoder's strict mode, the utf-8 buffer was being validated twice, I removed the second validation, non-asci decoding in strict mode is now 27–34% faster

Bench results (verry long, I wrote a gist file):

https://gist.github.com/mertcanaltin/42f2fe0808e85741bcc76e7f59a4229e

Short results:

util/text-decoder.js fatal=1 encoding='utf-8' content='one-byte-string'
  len=131072 ArrayBuffer       +31.14% ±1.90%
  len=131072 Buffer            +32.05% ±1.31%
  len=131072 SharedArrayBuffer +31.54% ±0.75%
  len=16384  ArrayBuffer       +28.06% ±1.73%
  len=16384  Buffer            +27.49% ±2.92%
  len=16384  SharedArrayBuffer +28.03% ±1.77%

util/text-decoder.js fatal=1 encoding='utf-8' content='two-byte-string'
  len=131072 ArrayBuffer       +33.67% ±1.17%
  len=131072 Buffer            +34.15% ±1.73%
  len=131072 SharedArrayBuffer +34.03% ±1.12%
  len=16384  ArrayBuffer       +31.13% ±1.71%
  len=16384  Buffer            +29.02% ±1.73%
  len=16384  SharedArrayBuffer +28.34% ±2.12%

util/text-decoder-stream.js unicode=1 fatal=1 encoding='utf-8'
  len=131072 Buffer            +11.66%
  len=131072 SharedArrayBuffer  +9.36%
  len=16384  Buffer             +8.08%
  len=16384  SharedArrayBuffer  +6.65%

[nodejs-github-bot]

Review requested:

• @nodejs/performance

[codecov]

Codecov Report

❌ Patch coverage is 29.62963% with 19 lines in your changes missing coverage. Please review.
✅ Project coverage is 90.03%. Comparing base (facd71e) to head (0df76ab).
⚠️ Report is 25 commits behind head on main.

Files with missing lines	Patch %	Lines
src/string_bytes.cc	25.00%	13 Missing and 5 partials ⚠️
src/encoding_binding.cc	66.66%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #63231      +/-   ##
==========================================
- Coverage   90.04%   90.03%   -0.01%     
==========================================
  Files         713      713              
  Lines      224950   224976      +26     
  Branches    42530    42542      +12     
==========================================
+ Hits       202548   202554       +6     
- Misses      14188    14191       +3     
- Partials     8214     8231      +17     

Files with missing lines	Coverage Δ
src/string_bytes.h	80.00% <ø> (ø)
src/encoding_binding.cc	53.22% <66.66%> (+0.30%)	⬆️
src/string_bytes.cc	71.34% <25.00%> (-3.29%)	⬇️

... and 34 files with indirect coverage changes

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[gurgunday]

Cc @ChALkeR if you want to take a look