Make early stop the default for checkpoint and expose a way to disable (#96866)
Why did I choose context manager instead of per-call? Early stopping is not part of the model definition, and depending on how a particular model is used, e.g., with PT2 or not we may or may not want to disable early stopping.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/96866
Approved by: https://github.com/albanD
