Add a delete button to clear all orders and deliveries

[JornHendrickx]

Often mistakes are made when creating an order or entering a delivery. These errors can accumulate, making it useful to delete all open orders and deliveries at the beginning of a semester.

Where:

• Stock -> Orders -> orange box "Delete all orders"
• Stock -> Deliveries -> orange box "Delete all deliveries"
• Stock -> Retours -> orange box "Delete all retours"