Add YOLOS (#16848)

* First draft

* Add YolosForObjectDetection

* Make forward pass work

* Add mid position embeddings

* Add interpolation of position encodings

* Add expected values

* Add YOLOS to tests

* Add integration test

* Support tiny model as well

* Support all models in conversion script

* Remove mid_pe_size attribute

* Make more tests pass

* Add model to README and fix config

* Add copied from statements

* Rename base_model_prefix to vit

* Add missing YOLOS_PRETRAINED_CONFIG_ARCHIVE_MAP

* Apply suggestions from code review

* Apply more suggestions from code review

* Convert remaining checkpoints

* Improve docstrings

* Add YolosFeatureExtractor

* Add feature extractor to docs

* Add corresponding tests

* Fix style

* Fix docs

* Apply suggestion from code review

* Fix bad rebase

* Fix some more bad rebase

* Fix missing character

* Improve docs and variable names

Co-authored-by: Niels Rogge <nielsrogge@Nielss-MacBook-Pro.local>

docs/source/en/_toctree.yml

@@ -376,6 +376,8 @@
       title: XLSR-Wav2Vec2
     - local: model_doc/xls_r
       title: XLS-R
+    - local: model_doc/yolos
+      title: YOLOS
     - local: model_doc/yoso
       title: YOSO
     title: Models