!str #15672 shallow shim of the new Streams DSL

* mostly Flow API
* initial Graph API
* positive and negative compilation tests
!str #15672 added all combinators from current Flow API

* combinator tests
!str #15672 add HTTP Pipeline with the new DSL

* implement graph operations as case class junctions
* add materialization method to ClosedFlow
Merge pull request #15724 from akka/wip-disable-osgi-for-akka-http-and-akka-http-core-for-now-ban

=pro Disable OSGi for akka-http and akka-http-core for now
!str #15672 add a way to retrieve Publsiher or Subscriber from Output/Input

* also remove ClosedFlow.as(...)
!str #15271 make transform() take a factory instead of Transformer
+ Makes reusing flows safe
+ Adds timerTransform for ops which need TimerTransformer
+ Adds TransformerLike in order to keep transform/timerTransform
  typesafe in respect to the passed in type og Transformer

Resolves #15271
Merge pull request #15698 from 2m/wip-typesafe-dsl

WIP Steams typesafe DSL
Merge pull request #15725 from ktoso/wip-transformerFactory-ktoso

!str #15271 make transform() take a factory instead of Transformer
!str #15121 MaterializerSettings now uses a config object

* made some apply() duplication trade-offs in FlowMaterializer companion
  for nicer API
+ made it possible to set namePrefix from Java API

Resolves #15121