Add _is_stateful property to OVBaseDecoderModel

[notsyncing]

What does this PR do?

Hello, when I try assisted generation with optimum-intel and openvino, it complains about

AttributeError: 'OVModelForCausalLM' object has no attribute '_is_stateful'. Did you mean: '_make_stateful'?

After adding this property to OVBaseDecoderModel, the error is gone, and assisted generation works.

Before submitting

• This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
• Did you make sure to update the documentation with your changes?
• Did you write any new necessary tests?

[IlyasMoutawwakil]

hello @notsyncing sorry I just noticed this PR, is this still an issue ?

[notsyncing]

hello @notsyncing sorry I just noticed this PR, is this still an issue ?

Yes, I'm manually patching it in my code, with latest optimum-intel git commit:

# original_model is an OVBaseDecoderModel
if hasattr(original_model, "stateful"):
   original_model._is_stateful = original_model.stateful

But I'm not sure if the PR is the way to fix this, there may be some more elegant solutions.

[IlyasMoutawwakil]

it seems to me that "_is_stateful" is no longer used in the lib https://github.com/search?q=repo%3Ahuggingface%2Foptimum-intel%20%22_is_stateful%22&type=code

[notsyncing]

it seems to me that "_is_stateful" is no longer used in the lib https://github.com/search?q=repo%3Ahuggingface%2Foptimum-intel%20%22_is_stateful%22&type=code

Yes, you are right, I tested again without my patch, it still works.
I'm closing this PR.