added alter table command to fluent query builder

demo/work.cpp

@@ -79,10 +79,11 @@ int main() {
     object::repository repo("Administration");
 
     auto result = repo.attach<admin::CollectionCenter>("collection_centers");
-    repo.create(pool);
-    repo.drop(pool);
+    // repo.create(pool);
+    // repo.drop(pool);
 
-    orm::session ses(pool);
+    utils::message_bus bus;
+    orm::session ses({bus, pool});
 
     result = ses.attach<admin::CollectionCenter>("collection_centers")
         .and_then([&ses] { return ses.attach<admin::UserDirectory>("user_directories"); })