Missing the auto-configuration of CoroutineSortingRepository

[nfrankel]

As mentioned in this post, the auto-configuration of proxies fail on the CoroutineSortingRepository.

Please check this project for a reproducer.

[sdeleuze]

As discussed with @christophstrobl, we should probably add a Coroutines R2DBC sample and refine the processor logic accordingly.

[sdeleuze]

See also the other repro project from #735.

[sdeleuze]

The root issue is that we don't use kotlin-reflect, so for methods using Coroutines, the return value detected in Object not the real return type because that's how Coroutines are compiled at bytecode level. Our fix is specific to this Spring Data Coroutines use case, but given how popular they are, I think it is worth to have it. I have created #769 to solve the root issue.