Display notification whether a customer is/is not linked to the accounting program in advance.

Now an error message comes up in the top right corner that the selected customer is not linked to the accounting program at the time the invoice is finalized. With a long text and a "Click here to link the customer" which does not work in the notification.

The best is to show a notification in advance at the top of the invoice as soon as a customer is chosen that is not linked to the admin/accounting program. With a trigger / dependsOn on the hint that it will be shown only if the selected customer is not linked.

In addition, previously a notification was also shown that the invoice was transferred to the accounting program. Could basically go away because that is also in the sidebar, but should the sidebar be collapsed they won't see this. Might be useful to put it back anyway. Also if it does not go through but in yellow(warning) and if it does go through in green.