[npu] change device to accelerator api (#5239)

* update accelerator

* fix timer

* fix amp

* update

* fix

* update bug

* add error raise

* fix autocast

* fix set device

* remove doc accelerator

* update doc

* update doc

* update doc

* use nullcontext

* update cpu

* update null context

* change time limit for example

* udpate

* update

* update

* update

* [npu] polish accelerator code

---------

Co-authored-by: Xuanlei Zhao <xuanlei.zhao@gmail.com>
Co-authored-by: zxl <43881818+oahzxl@users.noreply.github.com>

colossalai/utils/__init__.py

@@ -7,17 +7,12 @@ from .common import (
     is_ddp_ignored,
     set_seed,
 )
-from .device import IS_NPU_AVAILABLE, empty_cache, get_current_device, set_device, set_to_cuda, synchronize
 from .multi_tensor_apply import multi_tensor_applier
 from .tensor_detector import TensorDetector
 from .timer import MultiTimer, Timer
 
 __all__ = [
     "conditional_context",
-    "get_current_device",
-    "synchronize",
-    "empty_cache",
-    "set_to_cuda",
     "Timer",
     "MultiTimer",
     "multi_tensor_applier",
@@ -28,6 +23,4 @@ __all__ = [
     "free_storage",
     "set_seed",
     "is_ddp_ignored",
-    "set_device",
-    "IS_NPU_AVAILABLE",
 ]