🚨🚨🚨 [Refactor] Move third-party related utility files into integrations/ folder 🚨🚨🚨 (#25599)

* move deepspeed to `lib_integrations.deepspeed`

* more refactor

* oops

* fix slow tests

* Fix docs

* fix docs

* addess feedback

* address feedback

* final modifs for PEFT

* fixup

* ok now

* trigger CI

* trigger CI again

* Update docs/source/en/main_classes/deepspeed.md

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

* import from `integrations`

* address feedback

* revert removal of `deepspeed` module

* revert removal of `deepspeed` module

* fix conflicts

* ooops

* oops

* add deprecation warning

* place it on the top

* put `FutureWarning`

* fix conflicts with not_doctested.txt

* add back `bitsandbytes` module with a depr warning

* fix

* fix

* fixup

* oops

* fix doctests

---------

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

utils/not_doctested.txt

@@ -382,9 +382,11 @@ src/transformers/hyperparameter_search.py
 src/transformers/image_processing_utils.py
 src/transformers/image_transforms.py
 src/transformers/image_utils.py
-src/transformers/integrations.py
+src/transformers/integrations/bitsandbytes.py
+src/transformers/integrations/deepspeed.py
+src/transformers/integrations/integration_utils.py
+src/transformers/integrations/peft.py
 src/transformers/keras_callbacks.py
-src/transformers/lib_integrations/peft/peft_mixin.py
 src/transformers/modelcard.py
 src/transformers/modeling_flax_outputs.py
 src/transformers/modeling_flax_pytorch_utils.py