Visual Attention Network (VAN) (#16027)

* encoder works

* addded files

* norm in stage

* convertion script

* tests

* fix copies

* make fix-copies

* fixed __init__

* make fix-copies

* fix

* shapiro test needed

* make fix-copie

* minor changes

* make style + quality

* minor refactor conversion script

* rebase + tests

* removed unused variables

* updated doc

* toctree

* CI

* doc

* Apply suggestions from code review
Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>

* resolved conversations

* make fixup

* config passed to modules

* config passed to modules

* Apply suggestions from code review
Co-authored-by: NielsRogge <48327001+NielsRogge@users.noreply.github.com>

* conversations

* conversations

* copyrights

* normal test

* tests
Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>
Co-authored-by: NielsRogge <48327001+NielsRogge@users.noreply.github.com>

utils/documentation_tests.txt

@@ -18,6 +18,7 @@ src/transformers/models/swin/modeling_swin.py
 src/transformers/models/convnext/modeling_convnext.py
 src/transformers/models/poolformer/modeling_poolformer.py
 src/transformers/models/vit_mae/modeling_vit_mae.py
+src/transformers/models/van/modeling_van.py
 src/transformers/models/segformer/modeling_segformer.py
 src/transformers/models/vision_encoder_decoder/modeling_vision_encoder_decoder.py
 src/transformers/models/bart/modeling_bart.py