uniform logger manager in FleetAPI.
hidde API under distributed/utils which users don't need.

* refactor mp.

* update setup.py.

* update mp_layers.py for compatibility.

* add documents for mp_layers.py

* update init.py

* update collective.py.

* update.

* update mp_ops.py

* update.

* update code style.

* update code style.

* reconstruct_of_fleet_api

* update

* [OpAttr]Support VarDesc* and vector<VarDesc*> in Attribute

* add unittest for inference predictor

* fix sharding in eager

* support eager sharding

* rename eagerpylayer

* Replace np.bool/np.bool8 with np.bool_

* Replace np.object with np.object_

* Replace np.complex with np.complex128

* Replace np.float with np.float64

* Replace np.int with np.int_

* Rerun pre-commit for newer pre-commit configuration

* Use builtin bool instead of np.bool_ based on the context

* use yapf to format all python file

* yapf exclude two unittests file for they rely on writing and reading file, and format will break them

* disable diff_py_file because too many diff files cause command following failed

* fix_sharding3_offload

* fix_fp16dtype_bug

* fix recompute in mp

* fix recompute

* fix utest

* fix time

* refactor eager flags

* fix flags error when we switch from eager to dygraph

* fix ci problem

* fix ci

* fix ci

* merge develop and fix code style

* merge develop and fix code style

* fix op test error

* fix op test error

* fix op test error

* fix op test error

* fix op test error

* merge develop

* fix_sharding_group

* fix_sharding_group

* support param groups in grad_clip

* update

* modify for review