Rollup merge of #126127 - Alexendoo:other-trait-diag, r=pnkfelix

Spell out other trait diagnostic

I recently saw somebody confused about the diagnostic thinking it was suggesting to add an `as` cast. This change is longer but I think it's clearer

Author: jhpratt

compiler/rustc_trait_selection/src/traits/error_reporting/type_err_ctxt_ext.rs

@@ -2068,7 +2068,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                     if all_traits_equal {
                         format!("\n  {}", c.self_ty())
                     } else {
-                        format!("\n  {c}")
+                        format!("\n  `{}` implements `{}`", c.self_ty(), c.print_only_trait_path())
                     }
                 })
                 .collect();

tests/ui/binop/binary-op-suggest-deref.stderr

@@ -303,10 +303,10 @@ LL |     let _ = FOO & (*"Sized".to_string().into_boxed_str());
    |
    = help: the trait `BitAnd<str>` is not implemented for `i32`
    = help: the following other types implement trait `BitAnd<Rhs>`:
-             <&'a i32 as BitAnd<i32>>
-             <&i32 as BitAnd<&i32>>
-             <i32 as BitAnd<&i32>>
-             <i32 as BitAnd>
+             `&'a i32` implements `BitAnd<i32>`
+             `&i32` implements `BitAnd<&i32>`
+             `i32` implements `BitAnd<&i32>`
+             `i32` implements `BitAnd`
 
 error[E0277]: the size for values of type `str` cannot be known at compilation time
   --> $DIR/binary-op-suggest-deref.rs:78:17