make DataProvider an interface

Nobody has claimed this yet.

**Is your feature request related to a problem? Please describe.**
Currently, to extend the DataProvider, we have to be very explicit about generics, and do a fair amount of hackery to expose Models/Resources everywhere.
The aim here is to build an abstraction around the pieces in react-admin, to make wiring up APIs/Models/Views a lot more seamless within editor environments (fully static with plain JS for users).

**Describe the solution you'd like**
Currently, `DataProvider` is a TypeAlias, which are not injectable.
By allowing us to inject the `DataProvider`, we can cause `resourceName -> RaRecord` associations to propagate to all the hooks (`useGetList('cats')` should automatically find my Cat Model).

For now, changing it from `type` to `interface` might be enough, however I'm unsure of the fallout. I'll spin up a PR with a Demo to verify how it all goes, and so you have something physical to see.

I suspect this will be beneficial for the `no-code` project, however I've yet to do a dive into what that is in detail.

**Describe alternatives you've considered**
Wrapping + explicit types == Code too noisy

**Additional context**
n/a

Locate the DataProvider type alias and inspect its usages in the hooks and resource/model typings. Check how changing it to an interface affects generic propagation and injectable typing, then validate the behavior with the proposed demo; done means the resourceName-to-RaRecord association works across hooks without explicit generic wrappers.

Written by the indexing model from the issue text.