Add feature extraction mapping for automatic metadata update (#28944)

* add feature extraction mapping

* added prefix

* ruff check

* minor fix

* Update modeling_auto.py

* fix typo

* remove prefix to make variable public/importable

* Update src/transformers/models/auto/modeling_auto.py

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

* fixes

* addressed comments

* nit

* fix-copies

* remove from tests

* this should fix

* Update tests/models/convnextv2/test_modeling_convnextv2.py

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

* nits

---------

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

utils/check_repo.py

@@ -732,6 +732,8 @@ def check_all_auto_object_names_being_defined():
                         # module, if it's a private model defined in this file.
                         if name.endswith("MODEL_MAPPING_NAMES") and is_a_private_model(class_name):
                             continue
+                        if name.endswith("MODEL_FOR_IMAGE_MAPPING_NAMES") and is_a_private_model(class_name):
+                            continue
                         failures.append(
                             f"`{class_name}` appears in the mapping `{name}` but it is not defined in the library."
                         )