Fixes https://github.com/spring-projects/spring-integration/issues/8644 * Introduce an inner `DynamicHandlerRegistrationProxy` class to create an `IntegrationDynamicWebSocketHandlerRegistration` and map it into a provided `WebSocketHandler` when a `dynamicHandlerMapping` is in action. Co-authored-by: pziobron <64628007+pziobron@users.noreply.github.com>