Add Nystromformer (#14659)

* Initial commit

* Config and modelling changes

Added Nystromformer-specific attributes to config and removed all decoder functionality from modelling.

* Modelling and test changes

Added Nystrom approximation and removed decoder tests.

* Code quality fixes

* Modeling changes and conversion script

Initial commits to conversion script, modeling changes.

* Minor modeling changes and conversion script

* Modeling changes

* Correct modeling, add tests and documentation

* Code refactor

* Remove tokenizers

* Code refactor

* Update __init__.py

* Fix bugs

* Update src/transformers/__init__.py

Co-authored-by: NielsRogge <48327001+NielsRogge@users.noreply.github.com>

* Update src/transformers/__init__.py

Co-authored-by: NielsRogge <48327001+NielsRogge@users.noreply.github.com>

* Update src/transformers/models/nystromformer/__init__.py

Co-authored-by: NielsRogge <48327001+NielsRogge@users.noreply.github.com>

* Update docs/source/model_doc/nystromformer.mdx

Co-authored-by: NielsRogge <48327001+NielsRogge@users.noreply.github.com>

* Update src/transformers/models/nystromformer/configuration_nystromformer.py

Co-authored-by: NielsRogge <48327001+NielsRogge@users.noreply.github.com>

* Update src/transformers/models/nystromformer/configuration_nystromformer.py

Co-authored-by: NielsRogge <48327001+NielsRogge@users.noreply.github.com>

* Update src/transformers/models/nystromformer/configuration_nystromformer.py

Co-authored-by: NielsRogge <48327001+NielsRogge@users.noreply.github.com>

* Update src/transformers/models/nystromformer/configuration_nystromformer.py

Co-authored-by: NielsRogge <48327001+NielsRogge@users.noreply.github.com>

* Update src/transformers/models/nystromformer/convert_nystromformer_original_pytorch_checkpoint_to_pytorch.py

Co-authored-by: NielsRogge <48327001+NielsRogge@users.noreply.github.com>

* Update src/transformers/models/nystromformer/configuration_nystromformer.py

Co-authored-by: NielsRogge <48327001+NielsRogge@users.noreply.github.com>

* Update modeling and test_modeling

* Code refactor

* .rst to .mdx

* doc changes

* Doc changes

* Update modeling_nystromformer.py

* Doc changes

* Fix copies

* Apply suggestions from code review

Co-authored-by: NielsRogge <48327001+NielsRogge@users.noreply.github.com>

* Apply suggestions from code review

Co-authored-by: NielsRogge <48327001+NielsRogge@users.noreply.github.com>

* Update configuration_nystromformer.py

* Fix copies

* Update tests/test_modeling_nystromformer.py

Co-authored-by: NielsRogge <48327001+NielsRogge@users.noreply.github.com>

* Update test_modeling_nystromformer.py

* Apply suggestions from code review

Co-authored-by: Lysandre Debut <lysandre@huggingface.co>

* Fix code style

* Update modeling_nystromformer.py

* Update modeling_nystromformer.py

* Fix code style

* Reformat modeling file

* Update modeling_nystromformer.py

* Modify NystromformerForMultipleChoice

* Fix code quality

* Apply suggestions from code review

Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>

* Code style changes and torch.no_grad()

* make style

* Apply suggestions from code review

Co-authored-by: NielsRogge <48327001+NielsRogge@users.noreply.github.com>
Co-authored-by: Lysandre Debut <lysandre@huggingface.co>
Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>

docs/source/_toctree.yml

@@ -214,6 +214,8 @@
       title: MPNet
     - local: model_doc/mt5
       title: MT5
+    - local: model_doc/nystromformer
+      title: Nyströmformer
     - local: model_doc/openai-gpt
       title: OpenAI GPT
     - local: model_doc/gpt2