Upgrade Chalk again

The big change here is counting binders, not
variables (https://github.com/rust-lang/chalk/pull/360). We have to adapt to the
same scheme for our `Ty::Bound`. It's mostly fine though, even makes some things
more clear.

crates/ra_hir_ty/src/display.rs

@@ -303,7 +303,7 @@ impl HirDisplay for Ty {
                     }
                 }
             }
-            Ty::Bound(idx) => write!(f, "?{}", idx)?,
+            Ty::Bound(idx) => write!(f, "?{}.{}", idx.debruijn.depth(), idx.index)?,
             Ty::Dyn(predicates) | Ty::Opaque(predicates) => {
                 match self {
                     Ty::Dyn(_) => write!(f, "dyn ")?,