Prior to this commit, the `RSocketRequester.Builder` would allow to
configure directly annotated handlers for processing server requests.
This lead to a package tangle where the `o.s.messaging.rsocket` would
use classes from `o.s.messaging.rsocket.annotation.support` package.
This commit introduces the `ClientResponderFactory` interface for
configuring a responder on the client RSocket factory. Its goal is
to be compatible with future changes with a functional variant for
RSocket handlers.
Closes gh-23170
e7ecb83449