Add provider position field to ws_meta and view

Provider position is needed in coordinated recovery
between application and provider. Pass the position
info from provider to application to allow making
it durable.

dbsim/db_server_service.cpp

@@ -134,7 +134,8 @@ wsrep::view db::server_service::get_view(wsrep::client_service&,
         stored_view.capabilities(),
         my_idx,
         stored_view.protocol_version(),
-        stored_view.members()
+        stored_view.members(),
+        0
     );
     return my_view;
 }