Currently, the "Amounts to settle" button in the "Vendors" drop-down menu
opens a view showing all the account.move.line that are to be reconciled.
Also, they should only be shown when their residual is less than zero.
This commit makes it now so that when clicking on that button, only the amls
linked to a purchase journal are shown and another "Amounts to Settle" button
has been added in the "Customers" drop-down menu to show the amls linked to
a sale journal
task-3572482
closesodoo/odoo#140040
Signed-off-by: William André (wan) <wan@odoo.com>