Add REST API to toggle starred change state

Tests-by: David Ostrovsky <david@ostrovsky.org>
Change-Id: I4c1da5f7e0a1514e091eaab8c532b356c53f138a

gerrit-server/src/main/java/com/google/gerrit/server/change/ChangesCollection.java

@@ -58,7 +58,7 @@ public class ChangesCollection implements
   }
 
   @Override
-  public RestView<TopLevelResource> list() {
+  public QueryChanges list() {
     return queryFactory.get();
   }