Future PostgreSQL: Improvement to the Replication Protocol

PostgreSQL 15 introduces a new feature called READ_REPLICATION_SLOT command, developed by Aiven to improve the reliability of physical replication clients like pg_receivewal. The command allows these clients to read the current restart LSN and timeline associated with a replication slot, making them more reliable. This feature will help address issues encountered when using pg_receivewal and benefit other replication clients as well.