[All models] Extend config.output_attentions with output_attentions function arguments (#4538)

* DOC: Replace instances of ``config.output_attentions`` with function argument ``output_attentions``

* DOC: Apply Black Formatting

* Fix errors where output_attentions was undefined

* Remove output_attentions in classes per review

* Fix regressions on tests having `output_attention`

* Fix further regressions in tests relating to `output_attentions`

Ensure proper propagation of `output_attentions` as a function parameter
to all model subclasses

* Fix more regressions in `test_output_attentions`

* Fix issues with BertEncoder

* Rename related variables to `output_attentions`

* fix pytorch tests

* fix bert and gpt2 tf

* Fix most TF tests for `test_output_attentions`

* Fix linter errors and more TF tests

* fix conflicts

* DOC: Apply Black Formatting

* Fix errors where output_attentions was undefined

* Remove output_attentions in classes per review

* Fix regressions on tests having `output_attention`

* fix conflicts

* fix conflicts

* fix conflicts

* fix conflicts

* fix pytorch tests

* fix conflicts

* fix conflicts

* Fix linter errors and more TF tests

* fix tf tests

* make style

* fix isort

* improve output_attentions

* improve tensorflow

Co-authored-by: Patrick von Platen <patrick.v.platen@gmail.com>

tests/test_modeling_longformer.py

@@ -296,7 +296,7 @@ class LongformerModelTest(ModelTesterMixin, unittest.TestCase):
     test_headmasking = False  # head masking is not supported
     test_torchscript = False
 
-    all_model_classes = (LongformerForMaskedLM, LongformerModel) if is_torch_available() else ()
+    all_model_classes = (LongformerModel, LongformerForMaskedLM,) if is_torch_available() else ()
 
     def setUp(self):
         self.model_tester = LongformerModelTester(self)