Added support for ResponseMessage response type in @Controller message handling methods

[salmar]

Prior to this commit, the only way to override the destination to send the response of message handling methods was by using @sendto or @SendToUser, which doesn't allow building dynamic destinations.

The added ResponseMessage return type brings more flexibility when specifying the response message, which can be created using a builder, e.g

@MessageMapping("/dest")
public ResponseMessage<String> handle() {
        return ResponseMessage.destination("/queue/dest1").toUser("sergi").body("hi");
}

Other examples:

new ResponseMessage<String>("hi there", "/topic/dest1");
ResponseMessage.destination("/topic/dest1").body(PAYLOAD);
ResponseMessage.destinations("/queue/dest1", "/queue/dest2").toUser(USERNAME).body(PAYLOAD);
ResponseMessage.destination("/queue/dest1").toCurrentUser().body(PAYLOAD);
ResponseMessage.destination("/queue/dest1").toCurrentUserNoBroadcast().body(PAYLOAD);

Issue: SPR-12170

[salmar]

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[rstoyanchev]

Closing outdated, as per discussion under #16784.