Feature Request: `Value` construction with macro

[bdbai]

It would be super convenient to compose a complex Value directly from a diagnostic notation literal with a macro, similar to serde_json::json!.

[quininer]

I am not interested in this feature, you can use Value to construct it manually. I prefer to use the core::types construct, which will have less overhead. But if someone is willing to implement it, I am also happy to accept it.