[legacy] move communication and nn to legacy and refactor logger (#4671)

* [legacy] move communication to legacy (#4640)

* [legacy] refactor logger and clean up legacy codes (#4654)

* [legacy] make logger independent to gpc

* [legacy] make optim independent to registry

* [legacy] move test engine to legacy

* [legacy] move nn to legacy (#4656)

* [legacy] move nn to legacy

* [checkpointio] fix save hf config

* [test] remove useledd rpc pp test

* [legacy] fix nn init

* [example] skip tutorial hybriad parallel example

* [devops] test doc check

* [devops] test doc check

colossalai/utils/__init__.py

@@ -1,12 +1,14 @@
 from .activation_checkpoint import checkpoint
 from .checkpointing import load_checkpoint, save_checkpoint
 from .common import (
+    _cast_float,
     clip_grad_norm_fp32,
     conditional_context,
     copy_tensor_parallel_attributes,
     count_zeros_fp32,
     disposable,
     ensure_path_exists,
+    free_storage,
     is_ddp_ignored,
     is_dp_rank_0,
     is_model_parallel_parameter,
@@ -72,4 +74,6 @@ __all__ = [
     'disposable',
     'colo_set_cpu_memory_capacity',
     'colo_get_cpu_memory_capacity',
+    '_cast_float',
+    'free_storage',
 ]