Unique name problem

_Originally: https://github.com/virge-io/pricelist-frontend/issues/281_

The form to quickly create a wiet; is checking for uniqueness, globally.

It should honor the shop_group_id. (even when you remove that check box)

Form with problem:

Test cases:
Strawberry lemonade
Sour Mango

Start by locating the quick-create wiet form and the uniqueness validation it uses. Check how shop_group_id is handled when the checkbox is selected or removed, using the Strawberry lemonade and Sour Mango cases. Done means names are unique within the relevant shop group rather than globally, with tests covering the reported behavior.

Rédigé par le modèle d'indexation à partir du texte de l'issue.