Add a Node.js wrapper library

The implementation is very similar to the Python wrapper.

nodejs/README.md

@@ -0,0 +1,22 @@
+# libloot-nodejs
+
+An **experimental** Node.js wrapper around the libloot Rust implementation, built using [NAPI-RS](https://napi.rs/docs/concepts/class).
+
+## Build
+
+To build, first install Rust and Node.js, then run:
+
+```
+npm install
+npm run build
+```
+
+The tests can be run using:
+
+```
+npm test
+```
+
+## Usage notes
+
+- All errors are thrown as JavaScript `Error` values. The error message is the concatenated display text of all the recursive Rust errors from the libloot crate, with the exception of `PluginDataError` errors, which are turned into messages of the form `esplugin error, code <code>: <display text>`, where `<code>` is one of the esplugin error codes currently exposed by the C++ implementation of libloot.