#22903 Fix code snippeds

* move scala and java sources out of paradox sources
* replace relative paths with $code$ and $akka$
* fix broken includes

akka-docs/src/main/paradox/scala/additional/code/docs/faq/Faq.scala

@@ -1,30 +0,0 @@
-package docs.faq
-
-import akka.actor.Actor
-
-//#exhaustiveness-check
-object MyActor {
-  // these are the messages we accept
-  sealed abstract trait Message
-  final case class FooMessage(foo: String) extends Message
-  final case class BarMessage(bar: Int) extends Message
-
-  // these are the replies we send
-  sealed abstract trait Reply
-  final case class BazMessage(baz: String) extends Reply
-}
-
-class MyActor extends Actor {
-  import MyActor._
-  def receive = {
-    case message: Message => message match {
-      case BarMessage(bar) => sender() ! BazMessage("Got " + bar)
-      // warning here: 
-      // "match may not be exhaustive. It would fail on the following input: FooMessage(_)"
-      //#exhaustiveness-check
-      case FooMessage(_)   => // avoid the warning in our build logs
-      //#exhaustiveness-check
-    }
-  }
-}
-//#exhaustiveness-check

akka-docs/src/main/paradox/scala/additional/faq.md

@@ -79,7 +79,7 @@ exhaustiveness.
 Here is an example where the compiler will warn you that the match in
 receive isn't exhaustive:
 
-@@snip [Faq.scala](code/docs/faq/Faq.scala) { #exhaustiveness-check }
+@@snip [Faq.scala]($code$/scala/docs/faq/Faq.scala) { #exhaustiveness-check }
 
 ## Remoting
 

akka-docs/src/main/paradox/scala/additional/osgi.md

@@ -96,7 +96,7 @@ dynamic in this way. ActorRefs may safely be exposed to other bundles.
 To bootstrap Akka inside an OSGi environment, you can use the `akka.osgi.ActorSystemActivator` class
 to conveniently set up the ActorSystem.
 
-@@snip [Activator.scala]../../../../../akka-osgi/src/test/scala/docs/osgi/Activator.scala) { #Activator }
+@@snip [Activator.scala]($akka$/akka-osgi/src/test/scala/docs/osgi/Activator.scala) { #Activator }
 
 The goal here is to map the OSGi lifecycle more directly to the Akka lifecycle. The `ActorSystemActivator` creates
 the actor system with a class loader that finds resources (`application.conf` and `reference.conf` files) and classes