+ akka-cluster-metrics: new akka module

* new akka module split from akka-cluster
* provide sigar provisioning
* fix ewma usage
* resolve #16121
* see #16354

akka-cluster/src/multi-jvm/scala/akka/cluster/StressSpec.scala

@@ -3,6 +3,9 @@
  */
 package akka.cluster
 
+// TODO remove metrics 
+// FIXME this test is not migrated to metrics extension 
+
 import language.postfixOps
 import scala.annotation.tailrec
 import scala.collection.immutable