**What**
- Adds a step to `updateShippingOptionsWorkflow` and `createShippingOptionsWorkflow` that validates if the region prices being updated have corresponding regions configured.
**Why**
- Previously, if you tried to send a region price update for a region that had been deleted the backend would throw an error when attempting to insert the region price. The error comes from a not-null constraint in the db, but it is better to validate that the regions we are trying to create prices for exist.
Fixes CC-542
0efbcd2344