Inline the type annotations (if possible)

[jaraco]

This project has type annotations defined in .pyi files. Many of these annotations would be useful as inline.

However, due to the "wrapper" nature of this project and the fact that it deals with IO, the type annotations are very complicated, using overloads and providing types for functions that are just aliases.

In feature/inline-types, I started exploring what it would take to migrate the types. I was hoping to use something like retype, but that project is actively abandoned and has unfixed bugs for things like overloads.

If someone with some expertise would like to work on migrating the types, I'd appreciate the help.

[jaraco]

I got the commit wrong :(