Add a `hasItems` helper on the Product store coll

[phoenixbox]

What's this PR do?

Controls the presence of placeholder cards with the return value of a ProductStore helper called hasItems(productId)

Where should the reviewer start?

How should this be manually tested?

Create a new product and see the placeholder tickets

Create an item and see them disappear

What are the relevant tickets?

#3

Screenshots (if appropriate)