Implement const Destruct in old solver

compiler/rustc_next_trait_solver/src/solve/assembly/structural_traits.rs

@@ -712,6 +712,8 @@ pub(in crate::solve) fn extract_fn_def_from_const_callable<I: Interner>(
     }
 }
 
+// NOTE: Keep this in sync with `evaluate_host_effect_for_destruct_goal` in
+// the old solver, for as long as that exists.
 pub(in crate::solve) fn const_conditions_for_destruct<I: Interner>(
     cx: I,
     self_ty: I::Ty,