Add MultipleChoice to TFTrainer [WIP] (#4270)

* catch gpu len 1 set to gpu0

* Add mpc to trainer

* Add MPC for TF

* fix TF automodel for MPC and add Albert

* Apply style

* Fix import

* Note to self: double check

* Make shape None, None for datasetgenerator output shapes

* Add from_pt bool which doesnt seem to work

* Original checkpoint dir

* Fix docstrings for automodel

* Update readme and apply style

* Colab should probably not be from users

* Colabs should probably not be from users

* Add colab

* Update README.md

* Update README.md

* Cleanup __intit__

* Cleanup flake8 trailing comma

* Update src/transformers/training_args_tf.py

* Update src/transformers/modeling_tf_auto.py

Co-authored-by: Viktor Alm <viktoralm@pop-os.localdomain>
Co-authored-by: Julien Chaumond <chaumond@gmail.com>

examples/multiple-choice/README.md

@@ -29,3 +29,28 @@ Training with the defined hyper-parameters yields the following results:
 eval_acc = 0.8338998300509847
 eval_loss = 0.44457291918821606
 ```
+
+
+## Tensorflow
+
+```bash
+export SWAG_DIR=/path/to/swag_data_dir
+python ./examples/multiple-choice/run_tf_multiple_choice.py \
+--task_name swag \
+--model_name_or_path bert-base-cased \
+--do_train \
+--do_eval \
+--data_dir $SWAG_DIR \
+--learning_rate 5e-5 \
+--num_train_epochs 3 \
+--max_seq_length 80 \
+--output_dir models_bert/swag_base \
+--per_gpu_eval_batch_size=16 \
+--per_gpu_train_batch_size=16 \
+--logging-dir logs \
+--gradient_accumulation_steps 2 \
+--overwrite_output
+```
+
+# Run it in colab
+[![Open In Colab](https://colab.research.google.com/assets/colab-badge.svg)](https://colab.research.google.com/github/ViktorAlm/notebooks/blob/master/MPC_GPU_Demo_for_TF_and_PT.ipynb)