This PR just applies the changes from the following PRs:
[Datasets] Automatically cast tensor columns when building Pandas blocks. #26684
reverted by Revert "[Datasets] Automatically cast tensor columns when building Pandas blocks." #26921
[AIR - Datasets] Fix TensorDtype construction from string and fix example. #26904
This fixes the test failures introduced in the originally reverted PRs.
Signed-off-by: Amog Kamsetty <amogkamsetty@yahoo.com>
As discussed offline, allow configurability for feature columns and keep columns in BatchPredictor for better scoring UX on test datasets.
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.
