Test mode for shipments

[DjQuinnEXP]

What problem does this feature solve?

A proper testing mode would be useful so we can see if everything works according to the functionality that it should without creating actual shipments that would be sent to PostNL and possibly our test customers.

What should the solution look like?

An extra field in the configuration to select if you're on a live or test environment.
Based on that it'd change if you create an actual PostNL shipment or only use test data. If you use the test mode that'd also disable sending an email to the customer.
This all to prevent that test data would be used to send out actual orders and shipments.

Relevant log output

No response

Additional context

No response