ReScript language support

Issue for tracking the PR adding ReScript language support (and devcontainer)

Rationale: ReScript is a language that compiles directly to JavaScript (a bit like TypeScript) but has a very strict and "rust-like" hindley-milner style type system making it a really nice fit to use together with Rust.

This PR adds support for generating types for ReScript making it possible to create end-to-end typesafe apps with Rust and ReScript with extremely sound types.