Allow to annotate `export default` with `@type`

(updated, see below) TypeScript allows to set a type on a function
CC should allow that too
This will allow to define a function as a type in one file and then use it in implementation.
This way I can create interfaces for functions, import them in implementations and have type checking done by the compiler. Otherwise, I have manually add the parameters to the function which I don't want to do because it's wasting time since I already have function's types in a separate place. TypeScript in vs code does it properly as you can see on the screenshot.