Feature: Option to use 'unknown' instead of 'any'

Hi,

I configured my typescript project to be as strict as possible to prevent as many runtime errors as possible. This includes denying the explicit usage of the `any` type. Using `any` in typescript is always unsafe and should only be used with care.

A command line option like `--unknown-instead-of-any` would be very nice :)

At the moment I added a `sed` command in my `package.json` to automatically replace all `any` with `unknown` in the generated typescript file, but I might not be the only one who prefers `unknown` over `any`.

Kind regards,
Marcel