Ability to map require's to loaded JS deps

[chr15m]

I'd like to import existing .cljs libraries I've written without recompiling Scittle and in a way that's compatible with existing shadow-cljs code. The things I am requiring often depend on js requires, which are resolved at compile time by shadow-cljs. To satisfy that I need something like an "importmap" which will tell Scittle how to resolve a require to the right JS object that is already loaded in a script tag. For example:

(:require
  ["something" :as something])

If we could tell Scittle that "something" actually resolves to window.SomeThingy then that would solve the problem.

You mentioned :load-fn which I'll investigate.