Move dietary properties from ingredient model to product model

[jayaddison]

Describe the reason for these changes and the problem that they solve

The knowledge-graph currently represents dietary properties (vegetarian, gluten_free, ...) as flags attached to the returned product rather than the overall ingredient.

In general (we should document the domain model...), an ingredient is a given product in a certain quantity.

It makes sense that the quantity of a product does not affect any of the dietary properties it has, so it does seem logical for these properties to exist on the product.

Briefly summarize the changes

1. Move the dietary property flags from the RecipeIngredient model to the IngredientProduct model

How have the changes been tested?

1. Unit test coverage is updated