[feat] transfer_split or transfers own payment ID

[AnimusXCASH]

Now when we do transfer split we place multipayments under one transaction. However Transaction allows only for one payment id. If we can integrate payment_id inside the payments of the transaction, it would be easier for future companies building on XCASH make products.

to my knowledge if I remember correctly we are able on x-payments to withdraw 15 payments inside one transaction under one payment id. With it we could make 15 payments, each having unique payment ID on withdrawal