Migrate account_groups.email_only_authors to capability

Added a new schema to migrate the account_groups.email_only_authors flag
to the emailReviewers global capability in All-Projects.

Change-Id: I15d330f9aa04460c7f93eb216bd7f4157cf2eb43

gerrit-server/src/test/java/com/google/gerrit/testutil/InMemoryDatabase.java

@@ -117,6 +117,9 @@ public class InMemoryDatabase implements SchemaFactory<ReviewDb> {
                   .annotatedWith(GerritPersonIdent.class) //
                   .toProvider(GerritPersonIdentProvider.class);
 
+              bind(AllProjectsName.class)
+                  .toInstance(new AllProjectsName("All-Projects"));
+
               bind(GitRepositoryManager.class) //
                   .to(LocalDiskRepositoryManager.class);
             }