Declarative macro support

We will need support for declarative macros, since they can output types that needs to be exported.

* We can't use `cargo-expand` for that, because it also expands proc macro, meaning we lose the serde attributes that we need to support.
* I didnt find any project aimed at resolving a *declarative* macro, only *procedural macros*. My understanding is that we can make one by looking at the inner implementation of macros inside the compiler and extracting that logic. That's a lot of work, including the research to relevant bits in the Rust compiler.

I'm opened to suggestions on how to support that properly.

Start by researching the Rust compiler's declarative macro expansion internals and compare them with cargo-expand, which also expands procedural macros. Done means supporting declarative macros that output exportable types while preserving the serde attributes needed by typebinder.

Written by the indexing model from the issue text.