Explore possibilities of referencing outer data types from inner module.

[sviezypan]

When generating WIT files, there's a rule that all data types need to reside inside the module (except for WIT keywords like option, result, list etc)

E.g. the following would not work

struct AuctionId {
    auction_id: String,
}

#[golem_rust::create_wit_file]
mod auction_app {

    struct Auction {
        auction_id: Option<super::AuctionId>,
        name: String,
        description: String,
        starting_price: f32,
        deadline: Deadline,
    }
}

The reason is that macro create_wit_file can't really see tokens outside of module that it is annotating. Is there a possibility to work around that?