transformers

edfd82f5 - Change model outputs types to self-document outputs (#5438)

Change model outputs types to self-document outputs (#5438) * [WIP] Proposal for model outputs * All Bert models * Make CI green maybe? * Fix ONNX test * Isolate ModelOutput from pt and tf * Formatting * Add Electra models * Auto-generate docstrings from outputs * Add TF outputs * Add some BERT models * Revert TF side * Remove last traces of TF changes * Fail with a clear error message * Add Albert and work through Bart * Add CTRL and DistilBert * Formatting * Progress on Bart * Renames and finish Bart * Formatting * Fix last test * Add DPR * Finish Electra and add FlauBERT * Add GPT2 * Add Longformer * Add MMBT * Add MobileBert * Add GPT * Formatting * Add Reformer * Add Roberta * Add T5 * Add Transformer XL * Fix test * Add XLM + fix XLMForTokenClassification * Style + XLMRoberta * Add XLNet * Formatting * Add doc of return_tuple arg