Support QuestionAnswering Module for ModernBert based models. (#35566)

* push ModernBertForQuestionAnswering

* update ModernBertForQuestionAnswering

* update __init__ loading

* set imports for ModernBertForQuestionAnswering

* update ModernBertForQuestionAnswering

* remove debugging logs

* update init_weights method

* remove custom initialization for ModernBertForQuestionAnswering

* apply make fix-copies

* apply make style

* apply make fix-copies

* append ModernBertForQuestionAnswering to the pipeline supported models

* remove unused file

* remove invalid autoload value

* update en/model_doc/modernbert.md

* apply make fixup command

* make fixup

* Update dummies

* update usage tips for ModernBertForQuestionAnswering

* update usage tips for ModernBertForQuestionAnswering

* add init

* add lint

* add consistency

* update init test

* change text to trigger stuck text

* use self.loss_function instead of custom loss

By @Cyrilvallez

Co-authored-by: Cyril Vallez <cyril.vallez@gmail.com>

* Update modeling_modernbert.py

make comparable commit to even it out

* Match whitespace

* whitespace

---------

Co-authored-by: Matt <rocketknight1@gmail.com>
Co-authored-by: Orion Weller <wellerorion@gmail.com>
Co-authored-by: Orion Weller <31665361+orionw@users.noreply.github.com>
Co-authored-by: Cyril Vallez <cyril.vallez@gmail.com>

docs/source/en/model_doc/modernbert.md

@@ -60,6 +60,9 @@ A list of official Hugging Face and community (indicated by 🌎) resources to h
 
 - [Masked language modeling task guide](../tasks/masked_language_modeling)
 
+<PipelineTag pipeline="question-answering"/>
+
+- [`ModernBertForQuestionAnswering`] is supported by this [example script](https://github.com/huggingface/transformers/tree/main/examples/pytorch/question-answering) and [colab notebook](https://colab.research.google.com/github/huggingface/notebooks/blob/main/examples/question_answering.ipynb).
 
 ## ModernBertConfig
 
@@ -88,5 +91,15 @@ A list of official Hugging Face and community (indicated by 🌎) resources to h
 [[autodoc]] ModernBertForTokenClassification
     - forward
 
+## ModernBertForQuestionAnswering
+
+[[autodoc]] ModernBertForQuestionAnswering
+    - forward
+
+### Usage tips
+
+The ModernBert model can be fine-tuned using the HuggingFace Transformers library with its [official script](https://github.com/huggingface/transformers/blob/main/examples/pytorch/question-answering/run_qa.py) for question-answering tasks.
+
+
 </pt>
 </frameworkcontent>