+per #15424 Added PersistentView, deprecated View

A PersistentView works the same way as View did previously, except:

* it requires an `peristenceId` (no default is provided)
* messages given to `receive` are NOT wrapped in Persistent()

akka-streams not touched, will update them afterwards on different branch

Also solves #15436 by making persistentId in PersistentView abstract.

(cherry picked from commit dcafaf788236fe6d018388dd55d5bf9650ded696)

Conflicts:
	akka-docs/rst/java/lambda-persistence.rst
	akka-docs/rst/java/persistence.rst
	akka-docs/rst/scala/persistence.rst
	akka-persistence/src/main/scala/akka/persistence/Persistent.scala
	akka-persistence/src/main/scala/akka/persistence/View.scala

akka-samples/akka-sample-persistence-java-lambda/src/main/java/doc/LambdaPersistenceDocTest.java

@@ -496,15 +496,13 @@ public class LambdaPersistenceDocTest {
 
   static Object o11 = new Object() {
     //#view
-    class MyView extends AbstractView {
-      @Override
-      public String persistenceId() {
-        return "some-persistence-id";
-      }
+    class MyView extends AbstractPersistentView {
+      @Override public String persistenceId() { return "some-persistence-id"; }
+      @Override public String viewId() { return "some-persistence-id-view"; }
 
       public MyView() {
         receive(ReceiveBuilder.
-          match(Persistent.class, persistent -> {
+          match(Object.class, p -> isPersistent(),  persistent -> {
             // ...
           }).build()
         );

akka-samples/akka-sample-persistence-java-lambda/src/main/java/sample/persistence/ViewExample.java

@@ -45,26 +45,21 @@ public class ViewExample {
     }
   }
 
-  public static class ExampleView extends AbstractView {
+  public static class ExampleView extends AbstractPersistentView {
 
     private int numReplicated = 0;
 
-    @Override
-    public String viewId() {
+    @Override public String persistenceId() { return "persistentActor-5"; }
+    @Override public String viewId() {
       return "view-5";
     }
 
-    @Override
-    public String persistenceId() {
-      return "persistentActor-5";
-    }
-
     public ExampleView() {
       receive(ReceiveBuilder.
-        match(Persistent.class, p -> {
+        match(Object.class, m -> isPersistent(), msg -> {
           numReplicated += 1;
           System.out.println(String.format("view received %s (num replicated = %d)",
-            p.payload(),
+            msg,
             numReplicated));
         }).
         match(SnapshotOffer.class, so -> {

akka-samples/akka-sample-persistence-java-lambda/tutorial/index.html

@@ -81,7 +81,7 @@ snapshotting to reduce recovery time.
 
 <p>
 To run this example, go to the <a href="#run" class="shortcut">Run</a> tab, and run the application main class
-<b><code>sample.persistence.ViewExample</code></b>.
+<b><code>sample.persistence.PersistentViewExample</code></b>.
 </p>
 </div>