[IMP] account: default cash difference account

When a cash journal is used in POS, we need to have accounts to post the
difference between what it's supposed to be in the cash journal and what
we really have in the cashbox.

To help the user to configure his cash journal, we've added default
accounts for cash difference in the localisation. Those default values
are stored on the company and are use for the creation of cash journals
if no values are provided.

TASK-ID: 1934784