ENG-5751: Send involved partition IDs in FragmentTaskMessage for command
logging.
ENG-5751: Include the partition ID in the end-of-log message.
ENG-5751: Use the GlobalServiceElector to elect the RestoreAgent leader so that
it's colocated with the MPI.
ENG-5751: Let the command log reinitiator know if it's colocated with the MPI.
ENG-5751: New messages used for replaying multiparts.