Add Swin Transformer (#15085)

* Add all files

* Apply suggestions from code review

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

* Updates

* Apply suggestions from review

* Fix failing tests

* Update __init__.py

* Update configuration_swin.py

* Update auto_factory.py

* Fix pytests

* Apply suggestions from code review

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

* Fix tests and default checkpoint

* Fix Recursion error

* Code quality

* Remove copied from

* Update modeling_swin.py

* Code quality

* Update modeling_swin.py

* Apply suggestions from code review

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

* Apply suggestions from code review

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

* Apply suggestions from code review

* Fix feature extractor

* Fix code quality

* 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>

* Apply suggestions from code review

* Update configuration_swin.py

* Update default checkpoint

* 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 docs/source/model_doc/swin.mdx

Co-authored-by: Mishig Davaadorj <mishig.davaadorj@coloradocollege.edu>

* Update conversion script

* Reformat conversion script

Co-authored-by: NielsRogge <48327001+NielsRogge@users.noreply.github.com>
Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>
Co-authored-by: Mishig Davaadorj <mishig.davaadorj@coloradocollege.edu>

docs/source/_toctree.yml

@@ -268,6 +268,8 @@
       title: Splinter
     - local: model_doc/squeezebert
       title: SqueezeBERT
+    - local: model_doc/swin
+      title: Swin Transformer
     - local: model_doc/t5
       title: T5
     - local: model_doc/t5v1.1