[IMP] stock_account, anglo-saxon accounting: help to clear out interim accounts

Accounting entries made for invoices and stock valuation on the interim accounts (stock input/output accounts) are now reconciled together for both sales and purchases. This will definitively help to have those accounts zero-outed when all operations are processed.

The reconciliation is made as long as the stock valuation is set in real-time, whatever the costing method.

Note that change change also allow a particular use case to be solved: when a purchase is made in a foreign currency whose rate change between the incoming shipment reception and the bill validation (there will be an automated exchange rate entry created).

Was task 32331. Was PR #22483