Enable on_before_batch_transfer for DPStrategy and IPUAccelerator

[rohitgr7]

What does this PR do?

Call to on_before_batch_transfer shouldn't be limited to whether any strategy/accelerator supports explicit transfer to batches to the device. Users should still be able to use this for batch transforms, etc...

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cc @Borda @carmocca @awaelchli @ninginthecloud @rohitgr7 @akihironitta

[awaelchli]

Accept to unblock, but I disagree with it the same way I disagreed when the on_before and on_after hooks were originally introduced.

on_before_batch_transfer has no meaning when the transfer is handled internally by the accelerator.

[rohitgr7]

Accept to unblock, but I disagree with it the same way I disagreed when the on_before and on_after hooks were originally introduced.

on_before_batch_transfer has no meaning when the transfer is handled internally by the accelerator.

we can probably remove them if you have better recommendations here on how users can perform batch transformations on/off device?