Support untyped use in JavaScript applications?

[jasongwartz]

A lot of the benefit of using Pkl with TypeScript comes from the compile-time types generated from Pkl schemas. But a JavaScript application might still benefit from using the evaluator to load a Pkl module into the mapped JS runtime types.

There might be no extra work to do here (I wouldn't think any, really) but a working example of a JS project would be useful to have in the examples directory.