Allow ignoring stock levels for subscriptions

[keferboeck]

Desired Behavior

A flag that can be configured in initialisers so that stock levels either for certain line items or in general are being ignored. Assuring the order is being processed.

(Optional) Current Behavior

Currently when stock level is not sufficient to fulfil and order, the instalment fails and the actionable date will be moved into the future.

(Optional) Additional notes

Small businesses don't always have the resources to keep all stock levels accurate and they are losing a lot of money through mishandled instalments. Two of my customers requested that feature.

[fthobe]

Hey @keferboeck can the item be backordered in current config?

https://guides.solidus.io/advanced-solidus/stock-and-fulfillment/