no argpartition op in keras.ops

[jonbarron]

Hi all, I'm trying to use Keras 3 as a drop-in replacement for numpy, but several ops are missing, such as argpartition. Can this be added? A viable workaround in case torch doesn't have an equivalent op would be to have the torch backend just call np.sort(), as this is sufficient to satisfy the conditions for argpartition (it's a quicksort pivot basically, so fully-sorting the list is overkill but not "wrong").

[fchollet]

That's in scope for Keras, we can add it.

[fchollet]

This is now in the API at HEAD.