Add ViltForTokenClassification e.g. for Named-Entity-Recognition (NER) (#17924)

* Add ViltForTokenClassification e.g. for Named-Entity-Recognition (NER)

* Add ViltForTokenClassification e.g. for Named-Entity-Recognition (NER)

* provide classifier only text hidden states

* add test_for_token_classification

* Update src/transformers/models/vilt/modeling_vilt.py

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

* Update src/transformers/models/vilt/modeling_vilt.py

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

* Update src/transformers/models/vilt/modeling_vilt.py

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

* Update src/transformers/models/vilt/modeling_vilt.py

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

* add test_for_token_classification

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

docs/source/en/model_doc/vilt.mdx

@@ -87,3 +87,8 @@ This model was contributed by [nielsr](https://huggingface.co/nielsr). The origi
 
 [[autodoc]] ViltForImageAndTextRetrieval
     - forward
+
+## ViltForTokenClassification
+
+[[autodoc]] ViltForTokenClassification
+    - forward