Improve Delayer DSL (#8645)

* Improve Delayer DSL

Move `groupId` option from a `delay()` method arg to the `DelayerEndpointSpec`
to make it cleaner from code reading perspective
* Expose new DSL method based on just a `DelayerEndpointSpec` for Kotlin &v Groovy
* Deprecate multi-arg `delay()` methods in favor of `Consumer<DelayerEndpointSpec>`-based

* * Fix language and code style

src/reference/asciidoc/delayer.adoc

@@ -33,7 +33,8 @@ If you need to determine the delay for each message, you can also provide the Sp
 @Bean
 public IntegrationFlow flow() {
     return IntegrationFlow.from("input")
-            .delay("delayer.messageGroupId", d -> d
+            .delay(d -> d
+                    .messageGroupId("delayer.messageGroupId")
                     .defaultDelay(3_000L)
                     .delayExpression("headers['delay']"))
             .channel("output")
@@ -46,7 +47,8 @@ public IntegrationFlow flow() {
 @Bean
 fun flow() =
     integrationFlow("input") {
-        delay("delayer.messageGroupId") {
+        delay {
+            messageGroupId("delayer.messageGroupId")
             defaultDelay(3000L)
             delayExpression("headers['delay']")
         }

src/reference/asciidoc/groovy-dsl.adoc

@@ -35,7 +35,10 @@ flowLambda() {
         wireTap integrationFlow {
             channel { queue 'wireTapChannel' }
         }
-        delay 'delayGroup', { defaultDelay 100 }
+        delay {
+		    messageGroupId 'delayGroup'
+		    defaultDelay 100
+        }
         transform String, { it.toUpperCase() }
     }
 }