lib: add utf16 fast path for TextDecoder

[ChALkeR]

Tracking: #61041

Better reviewed with whitespace hidden.

Builds on top of #61549
Like that PR, this is based on the logic in https://github.com/ExodusOSS/bytes

Previously, ICU and string_decoder were used on with-intl and without-intl variants correspondingly for UTF-16 implementation. ICU path was slow, string_decoder path was wrong and lacked BE anyway.

Instead, just use the codepath from #61549 with simple UTF-16 decoding methods.

This:

1. Speeds up utf-16le decoding about 3x
2. Speeds up utf-16be decoding about 2x
3. Adds fatal utf-16le support to without-intl TextDecoder
4. Fixes utf-16le replacement for without-intl TextDecoder, previously it was silently returning wrong results
5. Adds utf-16be support (both fatal and replacement) to without-intl TextDecoder
6. Unifies the logic, using a single codepath everywhere for Unicode

Benchmarks

https://ci.nodejs.org/view/Node.js%20benchmark/job/benchmark-node-micro-benchmarks/1804/

[nodejs-github-bot]

Review requested:

• @nodejs/performance
• @nodejs/startup

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.70%. Comparing base (4f13746) to head (b1f8aa3).
⚠️ Report is 8 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #61559      +/-   ##
==========================================
- Coverage   89.72%   89.70%   -0.02%     
==========================================
  Files         675      675              
  Lines      204806   204824      +18     
  Branches    39355    39355              
==========================================
- Hits       183761   183738      -23     
- Misses      13330    13363      +33     
- Partials     7715     7723       +8     

Files with missing lines	Coverage Δ
lib/internal/encoding.js	99.83% <100.00%> (-0.17%)	⬇️
lib/internal/encoding/util.js	100.00% <100.00%> (ø)

... and 43 files with indirect coverage changes

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[ChALkeR]

This is quite slow esp when run 30 times on CI
I wanted to denoise it though as otherwise it's still noisy even on e.g. 2x less numbers
If slow benchmarks are an issue I can exclude this change