Shipping Round Trips

[fthobe]

Desired Behavior

Some transactions require an inbound shipment such as

• repairs (pick up the device to repair it and ship it again)
  trade-in solutions
• paid alterations
• customizations
• lab tests
  ...

The feature would require:
Inbound shipping stock_location selector in products
Inbound shipping shipping method
Using this flags shipping extensions could be extended to cover this feature.

Ref #5903