Project node views argument validator generates SQL error for numeric project nids

Issue Summary

While testing #22402: Recent issues block I discovered a bug in project_plugin_argument_validate_project_nid.inc -- if you use a numeric project nid argument, the query to find and validate the nid is broken since the SQL we pass to db_rewrite_sql() doesn't use an 'n' alias on {node} and therefore db_rewrite_sql() freaks out. I'll commit a fix momentarily, just wanted to open an issue about it first.