=str Move new dsl to scaladsl2 package
=str #15746 Rename flow classes
=str #15744 Hook-up transform to the AST nodes

* Removed unused parts of the new dsl, such as FlowGraph
* Materialization of transform, still with old way of terminal operators,
  input/output factories will come next
* New ActorBasedFlowMaterializer in impl2
Merge pull request #15765 from akka/wip-15744-newdsl-transform-patriknw

=str #15744 Hook-up transform to the AST nodes
!str #15121 MaterializerSettings now uses a config object

Resolves #15121
=tes #15777 simple, but stable fix to , or . sensitivity in spec

Solves #15777

Conflicts:
	akka-testkit/src/test/scala/akka/testkit/metrics/reporter/PrettyDurationSpec.scala
Merge pull request #15759 from ktoso/wip-reduce-weight-flow-materializer-ktoso

!str #15121 MaterializerSettings now uses a config object
Merge pull request #15789 from ktoso/port-prettydurationspec-ktoso

=tes #15777 simple, but stable fix to , or . sensitivity in spec (for Validation)
=str #15755 #15756 First stab at input/output factories

* New naming based on Source and Sink
=str #15755 #15756 correct variance annotations

- make HasNoX into pure marker traits
- make materialization type-safe
- remove casting when using EmptyPublisher
=str #15755 mandate materializer for IterableSource

* Source attach to top flow subscriber
=str #15755 implement Sources

* Implement IteratorSource
* and add tests for IterableSource and IteratorSource
* Implement ThunkSource
* Implement FutureSource
* Implement TickSource
=str #15756 Implement Sinks

* Implement FutureSink
* also, make PublisherSink an object
* Implement OnCompleteSink
* Implement ForeachSink
* Implement SubscriberSink
=str #15755 #15756 Some cleanup
=str #15755 #15756 rework Source/Sink materialization

The philosophy is that the FlowMaterializer has complete control over
how it interprets the AST, no restrictions. Therefore it only involves
one specified method: materialize() which returns a MaterializedFlow.
Within the ActorBasedFlowMaterializer we materialize Sources and Sinks
that implement the specified SimpleSource/SourceWithKey interfaces (same
for Sinks), others are not supported. These traits are extensible and
they require that an ActorBasedFlowMaterializer is passed into the
factory methods. Other materializers can of course interpret these AST
nodes differently, or they can use the actor-based facilities by
creating a suitable materializer for them to use.

This means that everything is fully extensible, but the infrastructure
we provide concretely for ourselves is built exactly for that and
nothing more. Overgeneralization would just lead nowhere.

Also made FutureSink isActive and implement it using a light-weight
Subscriber instead of a Flow/Transformer.
Merge pull request #15790 from akka/wip-15755-15756-source-sink-patriknw

=str #15755 #15756 source and sink
!str #15604: Removal of default fanout behavior
Merge pull request #15793 from drewhk/wip-15604-no-fanout-drewhk

!str #15604: Removal of default fanout
!hco #15800 mark `Content-Length` header private for now

Instances will only created during HTTP message parsing and its value will
then be provided as a field of one of the HttpEntity subclasses.
=hco fail pending tests faster