Introduce a friendly way to resume the job from externalized checkpoints automatically

Currently, it's quite a bit not friendly for users to recover job from the externalized checkpoint, user need to find the dedicate dir for the job which is not a easy thing when there are too many jobs. This ticket attend to introduce a more friendly way to allow the user to use the externalized checkpoint to do recovery.

The implementation steps are copied from the comments of StephanEwen in 9043

• We could make this an option where you pass a flag (-r) to automatically look for the latest checkpoint in a given directory.
• If more than one jobs checkpointed there before, this operation would fail.
• We might also need a way to have jobs not create the UUID subdirectory, otherwise the scanning for the latest checkpoint would not easily work.