API to enumerate a module's exported functions

hey there!

While working on updating wasm3 on txiki.js I tried to avoid including internal header files and just using the public API (wasm3.h). The one thing I'm missing, which forces me to include m3_env.h is an API for enumerating the functions in a module. I'm using this to implement the exports property of Module instances in JS.

Any chance we can get an API for this?