Test coverage: Using the "use_for_shipping" option with multishipping is not possible.

[naydav]

Need to add https://github.com/magento/graphql-ce/blob/2.3-develop/app/code/Magento/QuoteGraphQl/Model/Cart/SetBillingAddressOnCart.php#L95 case to:

\Magento\GraphQl\Quote\Customer\SetBillingAddressOnCartTest
\Magento\GraphQl\Quote\Guest\SetBillingAddressOnCartTest

Examples you could find in
https://github.com/magento/graphql-ce/tree/2.3-develop/dev/tests/api-functional/testsuite/Magento/GraphQl/Quote/Customer

https://github.com/magento/graphql-ce/tree/2.3-develop/dev/tests/api-functional/testsuite/Magento/GraphQl/Quote/Guest

[naydav]

Was covered in the scope of
#321
#330