Query opt-in for fetching vector properties

By default, vector properties shouldn't be fetched back when loading an entity (partial loading); this is tracked by #37277.

However, in some advanced scenarios, some sort of reranking is performed client-side, requiring the vector properties to be fetched back. For those cases, we should have an opt-in the user's can use on a per-query basis.

@AndriySvyryd proposed repurposing the `Include()`, which we currently use to indicate that a navigation should be eagerly loaded (e.g. via JOIN). That API looks like it can work quite nicely for also indicating that a vector property should be loaded.

As this is a relatively rare, advanced requirement, this is not currently planned for the 11.0 release; we'll evaluate when to do this based on user feedback and other factors.