Allow Regions to be picked using the Store Entity Picker

[philipdanielhayton]

I'd like to be able to select a Region using the Vendr.StoreEntityPicker.

At the moment it only allows us to pick Countries.

For more context, our use case is like this:

• The business delivers rentals to people staying in accommodation in a foreign country
• Delivery rates vary by region
• During checkout the user must select a region where they are staying, but often the customer doesn't know what region they're staying in (this happens more than you'd think 😅) so we built an autocomplete tool that automatically populates the delivery fields based on their accommodation.
• The accommodation details are stored in Umbraco, but we can't currently select the Region in a straight forward manner (for example, like you can with the Country), so we are currently using string lookups based on region codes. Obviously this is quite fragile and requires the editor to have access to the Settings section.