[FIX] account: make assignation of tax repartition and tags work in bank reconciliation widget and on misc operations

Bank reconciliation widget allows creating a writeoff with tax lines, in order to simulate both the invoice and the payment into a single entry, from one statement line. Before this fix, the tax repartition used by this feature was always the one defined for invoices. Also, in some cases, the amounts reported in the tax report had the wrong sign, because of the way the tax report applies the sign multiplicator on lines' balances. This multiplicator cannot be computed properly from a payment or miscellaneous operation, so we need to rather impact the sign of the tags directly.

With this fix, we guess whether or not we are refunding something from the data entered by the user, and modify the signs of the tags accordingly so that the tax has the same impact on the report as it would have had with an invoice doing the same operation.

closes odoo/odoo#54691

X-original-commit: ac2662b67c878eb2ef6e9462a0e6c9f1fbdb6adb
Related: odoo/enterprise#11948
Signed-off-by: Laurent Smet <smetl@users.noreply.github.com>