feat: Encoding API Improvements

[nabetti1720]

Description of changes

To improve compatibility with encodings supported by Node.js, the following actions have been taken.
https://nodejs.org/api/util.html#whatwg-supported-encodings

• For encodings supported by LLRT, modified so that they can also be specified by aliases.
• Reduced excessive normalization and made label judgments a little stricter.
• Since iso-8859-1 was an alias, it was managed by windows-1252.
• ENCODING_MAP was introduced with the expectation of improved maintenance and lookup performance.

Checklist

• Created unit tests in tests/unit and/or in Rust for my feature if needed
• Ran make fix to format JS and apply Clippy auto fixes
• Made sure my code didn't add any additional warnings: make check
• Updated documentation if needed (API.md/README.md/Other)

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[richarddavison]

Hi @nabetti1720! I like the aliasing and more simple approach. Not sure if this yields much performance benefit (except for maybe one less string allocation to normalize the key) but it's more maintainable for sore.

[nabetti1720]

Hi @richarddavison .
Yes. In the previous implementation, it was necessary to create a new enum when dealing with aliases that exceeded the normalization range (e.g., treating unicode-1-1-utf8 as utf-8), and this proposal was made to avoid this.

Also, we believe that by minimizing the normalization, we can now evaluate with the same string as the actual label.

Lastly, sorry. Regarding lookup performance, I believe it is equivalent to O(1) both previously and now. I will correct what I described as an improvement. :)