Clone SST Copy and Synchronization Together

The Cross-Engine Synchronization for Clone and Clone SST Copy were introduced independently for easier individual presentation, but since they are adjacent in the clone flow, the overall joint picture is needed too:

The main points here are:

1. The cross engine synchronization must happen after the precopy;
2. The sst copy, from the synchronization and InnoDB redo log archiving point of view, is an extension of the InnoDB page copy stage.