Complement of 998f8df6aa254266c015fab144ba290e1a386cf0
Extend the editability to the journal entry (account.move), taking
as criteria if there's no reconciliation made, which is the definitory
one.
It includes test for this new feature, both the mode propagation and
the editability check.
TT39850
This field was editable in previous version before invoice > move
refactoring, and it's logic to allow to change payment mode once the
invoice has been posted without the need of resetting it to draft.
Thus, the field has been changed to computed writable field, taking care
of the consequences at model level (compute) and view level (add the
field in views + proper attrs).
This commits adds tracking=True to the payment mode field as well to be
aware when and who the payment mode is changed in the invoice, no matter
if directly changed in draft, or through the change on the journal item.
TT39850
