Fix: PIL image load in Processing utils apply_chat_template

[abdokaseb]

What does this PR do?

This PR #36682 introduced the batch size for images, everything is working correctly but the check for image existence don't support the PPIL images. The len() function could work with path or other things. So I converted it to check is not None it works for both PIL images and paths or URLs

Note: I made the same fix for videos also

Fixes #40603

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@zucchini-nlp

[zucchini-nlp]

It will not work unfortunately, because each image can be either an empty list or an ImageInput. We will never get any None inputs at this point

The idea is to not pass images if it is an empty list of empty lists. If it has at least one ImageInput, then we pass it further

[abdokaseb]

@zucchini-nlp Thanks for reply.
However the empty list will generate False. See the last example please

In [5]: batch_images = [[], [], ["test.png"]]
   ...: any((im is not None) for im_list in batch_images for im in im_list)
Out[5]: True

In [6]: batch_images = [[], [], [Image.new("RGB", (100, 100), (0, 0, 0))]]
   ...: any((im is not None) for im_list in batch_images for im in im_list)
Out[6]: True

In [7]: batch_images = [[], [], ["http://test.com"]]
   ...: any((im is not None) for im_list in batch_images for im in im_list)
Out[7]: True

In [8]: batch_images = [[], [], []]
   ...: any((im is not None) for im_list in batch_images for im in im_list)
Out[8]: False

[zucchini-nlp]

Oh yeah, my bad, didn't notice we are iterating per single image and not batched sublist.

[zucchini-nlp]

Will merge when CI turns green, it has been a bit flaky lately

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