facet-core: `Debug` impl of `Def` is misleading, should use `PointerDef`s `Debug` impl instead

[Erik1000]

https://docs.rs/facet-core/0.44.3/src/facet_core/types/def/mod.rs.html#217-219

A &Foos ::SHAPE.def debug impl prints SmartPointer<Foo> which is wrong since &T is not a smart pointer.
That is due to:
https://docs.rs/facet-core/0.44.3/src/facet_core/types/def/mod.rs.html#217-219
which is Some due to the way Facet is implemented for &T
https://docs.rs/facet-core/0.44.3/src/facet_core/impls/core/reference.rs.html#252

Discovered with the following code:

#[cfg(test)]
mod tests {
    use facet::{Def, Facet, KnownPointer};
    use facet_reflect::Peek;

    #[derive(Debug, Facet)]
    struct Foo {
        value: String,
    }

    #[facet_testhelpers::test]
    fn shared_reference() {
        let a = Foo {
            value: "aaaa".to_string(),
        };
        println!("{:#?}", <&Foo as Facet<'_>>::SHAPE.def);
        assert!(
            matches!(<&Foo as Facet<'_>>::SHAPE.def, Def::Pointer(p) if p.known == Some(KnownPointer::SharedReference))
        );
        let ref_a: &Foo = &a;
        let ref_ref_a: &&Foo = &ref_a;
        let peek = Peek::new(ref_ref_a);
        println!("{:#?}", peek.shape().def); // `Undefined`
        assert!(
            matches!(peek.shape().def, Def::Pointer(p) if p.known == Some(KnownPointer::SharedReference))
        );
    }
}