Options to use std::any::type_name for Debug

[daxpedda]

I just stumbled onto the fact that often it is useful to use std::any::type_name instead of just skipping fields when implementing Debug.

Maybe something like:

#[derive_where(Debug)]
struct Test<T> {
    a: u8,
    #[derive_where(debug_type_name)]
    b: T,
}