Add a TypeScript declaration generator for a typed-function?

This is an idea that came up in the discussion for https://github.com/josdejong/mathjs/pull/2448. Since in some sense, typed-function is a library that adds runtime type-checking and overloading to JavaScript that has a similar flavor to TypeScript's compile-time type-checking and overloading, it would be nice if there were a way to generate a TypeScript declaration for a typed-function that would compile (as close as possible to) exactly when the actual JavaScript call generated will *not* throw a TypeError. Because the type conversion and matching rules are fairly complex, I think this could only be done as a facility provided by this module, since it sees/knows everything that is going on with an individual function.

One potentially significant stumbling block is to get the sort of type inference that's actually of value to TypeScript users, the declaration should have some information about what the return types of functions are. So I think this would really only be doable in a useful way if typed-function added return-type annotations. So I will add an issue for that possibility as well.