Accept `trust_remote_code` and ignore it in `PreTrainedModel.from_pretrained`
# What does this PR do?

Hope my understanding is correct. Let me know if I should apply the same change to `ProcessorMixin`, `PreTrainedTokenizerBase` etc.
_The documentation is not available anymore as the PR was closed or merged._<|||||>@sgugger FYI:

I applied the change to TF and Flax `PreTrainedModel` (which is necessary, at least for TF), as well as `PretrainedConfig`.
Leave the tokenizer class and feature extractor class for now