Derive `QueryArgs` for structs to provide named query arguments

Hello!

Would it be possible to execute queries like this :

```
#[derive(Queryable)]
struct MusicOutput {
pub id: Uuid,
pub name: String
}

let parameters = HashMap::from([
("artist", "John 5"),
]);
let music_output: Result = conn.query_required_single(
"select (
insert Artist {
name := $artist
} unless conflict on .name else (select Artist)
) {id, name}", ¶meters).await;
```

Start by locating the `Queryable` derive and the `query_required_single` entry point, then trace how query parameters are currently accepted. The issue's example shows the intended result: a struct should derive `QueryArgs` and provide named arguments for the query; verify this by compiling an equivalent example.

Written by the indexing model from the issue text.