Akka HTTP - Return HttpEntity.Strict as-is, do not convert to HttpEntity.Default (#4922)

Some response body types produce `HttpEntity.Strict` by using
`HttpEntity`
[constructor](https://github.com/softwaremill/tapir/blob/b001ab6ff176e36d5a34d0b5d0609bb9bdf91bf5/server/akka-http-server/src/main/scala/sttp/tapir/server/akkahttp/AkkaToResponseBody.scala#L50).

Advantage of `HttpEntity.Strict` is that the entity data (response in
this case) is available in a `ByteString`, which makes it easier when
one needs to implement a custom Akka HTTP directive that works with the
response data, for example a directive for custom response logging.

However, `AkkaBodyListener` matched this type as `UniversalEntity`, and
by calling `transformDataBytes`, the entity was converted to
`HttpEntity.Default`, which stores the data in a `Source`. However, to
obtain the response data from a `Source`, one basically needs to run a
Future and apply some timeout to make sure that obtaining response data
does not take too much time.

The purpose of this proposal is to keep `HttpEntity.Strict` as-is when
it is available.

Author: honzabazant

server/akka-http-server/src/main/scala/sttp/tapir/server/akkahttp/AkkaBodyListener.scala

@@ -16,6 +16,11 @@ class AkkaBodyListener(implicit ec: ExecutionContext) extends BodyListener[Futur
       case ws @ Left(_)               => cb(Success(())).map(_ => ws)
       case Right(e) if e.isKnownEmpty =>
         Future.successful(Right(e)).andThen { case _ => cb(Success(())) }
+      case Right(e: HttpEntity.Strict) =>
+        // The advantage of HttpEntity.Strict is that it has the data available in a ByteString, which makes it easier
+        // to implement custom directives that work with the data, such as custom response logging. Using the case
+        // below, the entity would be converted to HttpEntity.Default, which has the data available in a Stream.
+        Future.successful(Right(e)).andThen { case _ => cb(Success(())) }
       case Right(e: UniversalEntity) =>
         Future.successful(
           Right(

server/pekko-http-server/src/main/scala/sttp/tapir/server/pekkohttp/PekkoBodyListener.scala

@@ -16,6 +16,11 @@ class PekkoBodyListener(implicit ec: ExecutionContext) extends BodyListener[Futu
       case ws @ Left(_)               => cb(Success(())).map(_ => ws)
       case Right(e) if e.isKnownEmpty =>
         Future.successful(Right(e)).andThen { case _ => cb(Success(())) }
+      case Right(e: HttpEntity.Strict) =>
+        // The advantage of HttpEntity.Strict is that it has the data available in a ByteString, which makes it easier
+        // to implement custom directives that work with the data, such as custom response logging. Using the case
+        // below, the entity would be converted to HttpEntity.Default, which has the data available in a Stream.
+        Future.successful(Right(e)).andThen { case _ => cb(Success(())) }
       case Right(e: UniversalEntity) =>
         Future.successful(
           Right(