Extend Transformers Trainer Class to Enable CPU AMP and Integrate Intel Extension for PyTorch (#17138)

* init PR

* fix import ipex

* minor fix on bf16

* refine optimizer

* refine args notes

* refine code

* refine ipex optimize args

* refine half_precision_backend

* black format

* isort format

* isort format files

* flake8 format

* doc builder format

* refine codes

* remove jit and optim bits

* black preview format

* Update src/transformers/trainer.py

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

* refine code

* refine notes

* Update src/transformers/trainer.py

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

* Update src/transformers/trainer.py

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

* code refine

* add ipex ut

* add performance cpu doc

* link to the cpu doc from main perf doc

* install ipex into CI's docker

* Update perf_train_cpu.mdx

* Update docs/source/en/perf_train_cpu.mdx

Co-authored-by: Stas Bekman <stas00@users.noreply.github.com>

* Update perf_train_cpu.mdx

* Update perf_train_cpu.mdx

Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>
Co-authored-by: Stas Bekman <stas@stason.org>
Co-authored-by: Stas Bekman <stas00@users.noreply.github.com>

docs/source/en/_toctree.yml

@@ -85,6 +85,8 @@
     title: Training on one GPU
   - local: perf_train_gpu_many
     title: Training on many GPUs
+  - local: perf_train_cpu
+    title: Training on CPU
   - local: perf_hardware
     title: Custom hardware for training
   - local: testing