Ability to get the fully resolved name of functions and types

In my experience, it is currently really difficult to get the complete, fully resolved name of a function or type. This is especially annoying when one needs not just the name itself but also the namespace. So it would be great to have the ability to get the fully resolved name of functions and types from the perspective of a world. By “fully resolved” I mean that it includes (where applicable) the package, interface and the with `as` renamed function/type name.

Something kind of like:
```rust
struct FullName {
package: Option,
interface: Option,
name: Option,
as_: Option,
}
```
I haven’t completely figured out how names (and namespaces) work in Wit yet, so this may look different in practice.

Nell'issue non sono identificati file, test o punti di ingresso; inizia tracciando il modo in cui wit-bindgen rappresenta i mondi, i package, le interfacce e gli elementi rinominati di WIT. Esamina il comportamento esistente della risoluzione dei nomi e i test pertinenti, quindi considera completata la richiesta quando un'API concordata espone i componenti completamente risolti descritti nell'issue.

Scritto dal modello di indicizzazione a partire dal testo della issue.