PLbart support

[FahadEbrahim]

Hi,

This is a PR to add the PLBART model written in the following paper. The original code is available at the following link. It follows the BART architecture, so, I followed the same style.

This is my first PR, so apologies in advance for any errors and I'd appreciate your feedback and guidance.

Thanks,
Fahad.

[calpt]

Hey @FahadEbrahim,

Thank you so much for working on this! We'll look into your PR more closely in the coming days. In the meantime, it would be great if you could continue to work on making the failing checks passing and let us know if you need any help on that!

[FahadEbrahim]

Thank you @calpt for your kind reply.

The testing of the models and the methods were successful.
But I'd appreciate your review conceptually (if there are differences between PLBart and BART that I'm unaware of)

I was having an issue with the first test of code quality. It was due to not cloning the repo recursively.
It's been fixed now.

[calpt]

Finished a review pass of the changes in this PR and everything looks good to me (just one minor comment)! Would be awesome to see any adapters you trained with this implementation on the hub.

After comments & merge conflicts are resolved, we're good to merge from our side. Thanks again for working on this!

[FahadEbrahim]

Thank you @calpt for reviewing the PR. The conflict has been fixed.
Please let me know if anything can be modified.