Support for fetch reference (e.g. for Relay)

[taybenlor]

Hi, I love the getData and useResource pattern, the DX would be really nice for straight fetching data.

Relay doesn't set up its API in a way that would work nicely with this approach. It has two main functions:

// In your routes
const queryRef = loadQuery(/* ... */);

// In your component
const { data } = usePreloadedQuery(queryRef, /*... */);

Instead of using a promise to figure out if the fetch is complete, it uses a reference that acts as a handle on the request. This would work okay (if a bit strange) with getData and useResource, I could just ignore the loading and error statuses. Except that the queryRef needs to be actively disposed when it is no longer displayed.

Potentially a solution would be to add a more customisable get and dispose combo of options to the router config.