!str #16992 Rework Source and Sink name parameter

* Remove name parameter (no overloads), naming is performed using `.withAttributes` or the new
  convenience `.named`. Those adds the OperationAttribute.Name and also change the name of the
  shape Inlet and Outlet.

* Remove Source/Sink parameter list for 0 parameter methods,
  this allows usage of `Sink.head` instead of `Sink.head()`

akka-http-testkit/src/main/scala/akka/http/testkit/RouteTestResultComponent.scala

@@ -96,6 +96,6 @@ trait RouteTestResultComponent {
       failTest("Request was neither completed nor rejected within " + timeout)
 
     private def awaitAllElements[T](data: Source[T, _]): immutable.Seq[T] =
-      data.grouped(100000).runWith(Sink.head()).awaitResult(timeout)
+      data.grouped(100000).runWith(Sink.head).awaitResult(timeout)
   }
 }