Change E0369 diagnostic give note information for foreign items.

Make it easy for developers to understand why the binop cannot be applied.

fixes #125631

tests/ui/array-slice-vec/vec-res-add.stderr

@@ -5,6 +5,11 @@ LL |     let k = i + j;
    |             - ^ - Vec<R>
    |             |
    |             Vec<R>
+   |
+note: the foreign item type `Vec<R>` doesn't implement `Add`
+  --> $SRC_DIR/alloc/src/vec/mod.rs:LL:COL
+   |
+   = note: not implement `Add`
 
 error: aborting due to 1 previous error