MSN (Masked Siamese Networks) for ViT (#18815)

* feat: modeling and conversion scripts for msn.

* chore: change license year.

* chore: remove unneeded modules.

* feat: direct loading of state_dict from remote url.

* fix: import paths.

* add: rest of the files.

* add and fix rest of the files.

Co-authored-by: Niels <niels.rogge1@gmail.com>

* chore: formatting.

* code quality fix.

* chore: remove pooler.

* feat: add classification top.

* fix: configuration object.

* add: initial test cases (one failing).

* fix: basemodeloutput.

* add: caution on using the classification head.

* add: rest of the model related files.

* add: vit msn readme.

* fix: copied from statement.

* fix: dummy objects.

* add: ViTMSNPreTrainedModel to inits.

* fix: repo consistency.

* minor change in the model doc.

* fix: tests.

* Empty-Commit

* Update src/transformers/models/vit_msn/configuration_vit_msn.py

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

* address PR comments.

* Update src/transformers/models/vit_msn/modeling_vit_msn.py

Co-authored-by: amyeroberts <22614925+amyeroberts@users.noreply.github.com>

* chore: put model in no_grad() and formatting.

Co-authored-by: Niels <niels.rogge1@gmail.com>
Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>
Co-authored-by: amyeroberts <22614925+amyeroberts@users.noreply.github.com>

utils/documentation_tests.txt

@@ -84,6 +84,7 @@ src/transformers/models/vision_encoder_decoder/modeling_vision_encoder_decoder.p
 src/transformers/models/vit/modeling_vit.py
 src/transformers/models/vit/modeling_tf_vit.py
 src/transformers/models/vit_mae/modeling_vit_mae.py
+src/transformers/models/vit_msn/modeling_vit_msn.py
 src/transformers/models/wav2vec2/modeling_wav2vec2.py
 src/transformers/models/wav2vec2/tokenization_wav2vec2.py
 src/transformers/models/wav2vec2_conformer/modeling_wav2vec2_conformer.py