Clean TF ConvBert
# What does this PR do?

This PR aims to clean TF ConvBert by adding explicit keyword arguments, typing and update the documentation in the model implementation to make it easier to understand and read.

I don't understand this PR, I disagree with your proposal of adding keyword names when they're not required and don't help readability.

Mentioned here https://github.com/huggingface/transformers/pull/9788#discussion_r564365003 and here https://github.com/huggingface/transformers/pull/9788#discussion_r564373664.

Same goes for the BART refactor.<|||||>I have applied the same changes than in the #9788 PR. Should I remove all the keyword names and keep only the typing parts?