🚨 Delete duplicate code in backbone utils (#43323)
* draft
* first make it work, then make pretty
* :eyes:
* unused attributes?
* everythgin we need is in the config!
* push
* update
* update
* fixes
* forgot
* push more changes
* move it out from mxin
* last test fixes i hope
* delete backbone utils from utils
* docs
* more docs updates
* remove backbone from args
* docstring
* get rid of circular import and revert utils/backbonutils for BC
* fix more tests
* modular
* style run
* Update src/transformers/modeling_backbone_utils.py
Co-authored-by: Yoni Gozlan <74535834+yonigozlan@users.noreply.github.com>
* Update src/transformers/modeling_backbone_utils.py
Co-authored-by: Yoni Gozlan <74535834+yonigozlan@users.noreply.github.com>
* set and align output features from single entrypoint
* move init_backbone to '__init__'
* calling init with timm backbone
* maybe fix test
* fix tests
* fix more and new models as well
* fix last test, maybe will move them to a common file
* fix repo
* fix repo
* tests unified, cannot be in common because models are very different
* add in init
* make comment more detailed for future us
* fix modular
* update tests after DETR refactor
* rename `backbone_utils`
* delete bare `is_timm_available`
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Co-authored-by: Yoni Gozlan <74535834+yonigozlan@users.noreply.github.com>
