[FIX] account: reconciled with forced `amount_currency`

This is possible to create bank statements
forcing the amount in the foreign currency,
along with the bank account currency, and therefore
to force the foreign currency rate.

In such a case, when reconciling the journal items,
the currency rate conversion must not be done
against the currency rates written in database,
in the rates records, at that date, but with
the rate that was forced in the bank statement.

opw-676048