Add native support for RSocketExchange.

This commit introduces new AOT processors that look for
`@RSocketExchange` annotated methods on interfaces implemented by beans
and registers reachability metadata accordingly:

* JDK proxies for the beans themselves
* invocation reflection for annotated methods
* binding reflection for arguments and return types

This allows to compile such clients to Native Images.

Closes gh-29877

spring-messaging/src/main/resources/META-INF/spring/aot.factories

@@ -0,0 +1,2 @@
+org.springframework.beans.factory.aot.BeanRegistrationAotProcessor=\
+org.springframework.messaging.rsocket.service.RSocketExchangeBeanRegistrationAotProcessor