Bug 25655: Store actual cost in foreign currency and currency from the invoice

Bug 25655: Store actual cost in foreign currency and currency from the invoice

Bug 24158 allows to calculate the actual cost on time of receive from a foreign currency.
This new enhancement is storing the price and the currency in database, into two new columns
invoice_unitprice an invoice_currency

Test plan:
Create a new order with several items to receive
Receive one or more items, and tick "change currency" on the order
receive page
Select a currency and finish the receiving
In DB notice that the price and the currency have been stored.
Receive remaining items and confirm that the form is prefilled with
previous price and currency

Sponsored-by: The Research University in the Helmholtz Association (KIT)
Signed-off-by: Michaela Sieber <michaela.sieber@kit.edu>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>