`order_by` should be a list but can be an object

### What is the current behavior?

`order_by: [todos_order_by!]` means that it must be a list, however it also works with `order_by: {title: asc}`. This looks like a bug / broken implementation to me. Or is there any GraphQL feature that allows this?

### What is the expected behavior?

Using an object instead of a list should cause an error.
There should be an extra field like `order_by_many` for sorting by a list of columns.

Start by reproducing issue #9829 with the `order_by` and `todos_order_by` inputs described in the report, then locate the schema and input-validation entry points that handle them. Done means an object supplied where a list is declared is rejected, while the supported list form remains usable and any replacement such as `order_by_many` is documented by the resulting tests or schema behavior.

Written by the indexing model from the issue text.