Support public re-export of private module

[notdanilo]

We want to support this:

mod thing;
pub use thing::*;

It currently doesn't work because the temporary FFI project uses the full path like use crate::thing::Thing;
So we need to track down where the object is being publicly exposed.

[notdanilo]

A process to deal with relative path imports, absolute path imports and wildcard imports are implemented in #79.