chore(libzip): set TEXTDECODER to 2

[paul-soporan]

What's the problem this PR addresses?

From https://github.com/emscripten-core/emscripten/blob/f5379af65490290aaae466a31b29b5d8e556bb60/src/settings.js#L1639-L1645:

If set to 2, we assume TextDecoder is present and usable, and do not emit
any JS code to fall back if it is missing.

Since TextDecoder has been fully available since Node 11.0.0, we can make Emscripten always use it.

How did you fix it?

Set -s TEXTDECODER=2.

	libzipAsync.js size	Bundle size
Before	377588	2813588
After	376820	2812671

Performance is the same.

Checklist

• I have read the Contributing Guide.

• I have set the packages that need to be released for my changes to be effective.

• I will check that all automated PR checks pass before the PR gets reviewed.

[merceyz]

LGTM!

Performance is the same.

We could still make the PR title perf: since the bundle size is reduced 🤔