The package "ml" should be renamed to "air".
Main question: Keep a `ml.py` with `from ray.air import *` for some level of backwards compatibility?
I'd go for no to force people to use the new structure.
This PR
- adds an example on how to run Ray Train and log results to weights & biases
- adds functionality to the W&B plugin to store checkpoints
- fixes a bug introduced in #24017
- Adds a CI utility script to setup credentials
- Adds a CI utility script to remove test state from external services cc @simon-mo