emsdk

Update Node to 20.18.0 LTS and add support for Windows on ARM64 to Node packages. (#1473)

Earlier Node 18.20.3 LTS did not yet support Windows on ARM64 builds.

Node 20.18.0 LTS is released on
https://nodejs.org/en/blog/release/v20.18.0.

This update currently only affects the "compiled from source" builds,
and not the Google precompiled releases.