Add nodejs embedding example

[asprouse]

Description of the change

Adds an example of embedding a Javy-compiled WASM module in a Node.js host application. Based on work https://github.com/asprouse/javy-nodejs-example

Why am I making this change?

There is not an existing example.

Checklist

• I've updated the relevant CHANGELOG files if necessary. Changes to javy-cli and javy-core do not require updating CHANGELOG files.
• I've updated the relevant crate versions if necessary. Versioning policy for library crates
• I've updated documentation including crate documentation if necessary.

[jeffcharles]

Looks good to me! Thank you for contributing!