Create a catalogProduct query in graphQL

[spencern]

Summary
Create a query to retrieve a single catalog product by the provided slug or ID.

Implementation
The catalogProduct query should have the following signature

catalogProduct(slugOrId: String): CatalogItemProduct

See #4105 for schema detail.

Acceptance Criteria
Using GraphQL, I can use the catalogProduct(slugOrId: String): CatalogItemProduct query to get a single CatalogProduct by it's slug.