* fluid clean: remove parallel and parallel_helper api

* fix: fix the import path.

* fix DataParallel imports issue

* delete legacy dygraph code in python/paddle/distributed

* refine

* Fix bug of reduce_sum op. When input.numel() > INT32_MAX, its result
is wrong.

* Remove climits.

* Clean fluid API in paddle/distributed and paddle/fleetx folders.
Include following files:
python/paddle/distributed/__init__.py
python/paddle/distributed/collective.py
python/paddle/distributed/fleet/utils/fs.py
python/paddle/distributed/fleet/utils/hybrid_parallel_inference.py
python/paddle/distributed/fleet/utils/hybrid_parallel_util.py
python/paddle/distributed/fleet/utils/internal_storage.py
python/paddle/distributed/launch/context/device.py
python/paddle/distributed/parallel.py
python/paddle/distributed/parallel_with_gloo.py
python/paddle/distributed/spawn.py
python/paddle/framework/__init__.py
To be mentioned, 'paddle.fluid.dygraph.parallel.ParallelEnv'
 and 'fluid.framework.core' keeps unchanged in those files.
ParallelEnv is used by paddle.fluid.dygraph.parallel.DataParallel.
However, APIs in paddle.fluid.dygraph.parallel can't be
migrated to paddle.distributed, as there exists cyclic import
dependencies in modules like paddle.static, paddle.tensor. And
'fluid.framework.core' will be changed to import framework.core
after fluid.core is transmitted.

* Change TODO authors.

* isort all files

* revert conflicting files

* revert conflicting files

* revert conflicting files

* add fused_allreduce_gradients_with_group

* add scale

* fix ci

* update config

* re-blacken python code

* temporarily disable date and diff_py_file

* skip a format

* [CodeStyle][F401] remove unused import in python/paddle/distributed

* remove pass

* empty commit

* Fix ValueError: list.remove(x): x not in list for meta_optimizer_names.

Fix ValueError: list.remove(x): x not in list for meta_optimizer_names.

* Fix split import.

Fix split import.

* add noqa after meta_optimizers in factory

* restort collective ops

* expand `import *`

* add noqa after required imports

* try to fix APIs without core.ops

* Revert "try to fix APIs without core.ops"

This reverts commit 6172beaf601e84bf61f2490c12c4739f0edaa5eb.

* fix an increment

* empty commit

* add noqa after required imports

* expand `import *`, fix ci error
Co-authored-by: NShuangchi He <34329208+Yulv-git@users.noreply.github.com>

* fix bugs of mp

* fix bugs of mp

* update

* update

* fix bug

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

* reconstruct_of_fleet_api

* update

* fix bugs of reducer

* update

* update

* 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

* remove unrequired ut cases

* update

* fix bugs

* update

* fix bug of check_inf

* fix allreduce

* Add solutions to PyLayer which is unsupported in DataParallel

* modify note format for parallel.py

* modify docs of dataparallel

* add docs of dp with pylayer

* modify docs format

* modify example format

* change example of dp with pylayer

* add unittest for dp with pylayer

* modify ut

* merge latest codes

* update

* modify for CI-Coverage

* modify text-indent

* dygraph sharding

* update unitest hybrid_parallel_communicate_group

* fix precision of mp

* fix bug of seed

* fix dp

* print group

* fix model parallel

* rm parallel_help.py

* add embedding

* add clip/check

* add amp & clip grad in dygraph

* add logging

* support dp & mp