RSocket server auto-configuration with Spring Messaging

[spencergibb]

Framework issue spring-projects/spring-framework#21292

Ongoing work https://github.com/rstoyanchev/spring-framework/tree/rsocket

Possible candidates for autoconfiguration:
https://github.com/rstoyanchev/spring-framework/blob/cbd5e252702268970cad8de7873bcc605d3dddb3/spring-messaging/src/test/java/org/springframework/messaging/rsocket/RSocketClientToServerIntegrationTests.java#L68-L90

https://github.com/rstoyanchev/spring-framework/blob/cbd5e252702268970cad8de7873bcc605d3dddb3/spring-messaging/src/test/java/org/springframework/messaging/rsocket/RSocketClientToServerIntegrationTests.java#L249-L275