lib: add utf16 fast path for TextDecoder

[ChALkeR]

Tracking: #61041

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

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 5x
2. Speeds up utf-16be decoding about 3x
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

TODO

[nodejs-github-bot]

Review requested:

• @nodejs/performance
• @nodejs/startup