Add type hints for TF MPNet models
Based on Issue https://github.com/huggingface/transformers/issues/16059

I have added type hints for the all the Tensorflow MPNet models.

@Rocketknight1 Could you kindly check if this is fine?

Thanks in advance.
Thanks @Rocketknight1 😊.<|||||>_The documentation is not available anymore as the PR was closed or merged._