[FIX] account: manual reconciliation through the wizard on journal items were...

[FIX] account: manual reconciliation through the wizard on journal items were giving weird results. OPW 678153.

Symptoms: running a full reconciliation manually with that wizard was resulting in not fully reconciled aml altough the total in company currency and in secondary currency were perfectly matched. Full use case described in added test test_manual_reconcile_wizard_opw678153.
Problems:
 - The system was processing by pair of aml and creating exchange rate entry/full reconciliation as soon as possible whereas in that case it needs to be postponed at the end of the manual reconciliation otherwise some entries would be excluded from processing.
 - Another problem was that because of this batch processing, we ended with unconsistent amount_residual_currency values for some entries that were fully reconciled in company currency but not in foreign currency (also negative amount_residual_currency for a debit line which should never happens)... To solve that, we now process the manual full reconciliation in two steps: only in company currency first, then in secondary currency if needed. A small adaptation in the payment widget of invoices was needed for that too.