=pro run multi-jvm tests when validating pr

* addunidoc task via an AutoPlugin that depends on PrValidation and Unidoc autoplugins
* separate cli option logic to a case class
* remove autoplugin for root project

project/Sample.scala

@@ -5,6 +5,17 @@ import sbt.Keys._
 
 object Sample {
 
+  object CliOptions {
+    /**
+     * Aggregated sample builds are transformed by swapping library dependencies to project ones.
+     * This does work play well with dbuild and breaks scala community build. Therefore it was made
+     * optional.
+     *
+     * Default: true
+     */
+    val aggregateSamples  = sys.props.getOrElse("akka.build.aggregateSamples", "true").toBoolean
+  }
+
   final val akkaOrganization = "com.typesafe.akka"
 
   def buildTransformer = (ti: BuildLoader.TransformInfo) => ti.base.name match {