Adding Magento_SalesGraphQlAux to provide order state

[fooman]

To be able to address https://github.com/magento/pwa-studio/issues/3716 it is helpful to have access to the order state. This pull request adds this for the following query:

query {
    customer {
        orders {
            items {
                order_number
                state
            }
        }
    }
}