* move fc from fluid to paddle2.0

* fix unit test

* fix some examples

* fix some examples

* Clean fliud hash

* clean fluid grid_sampler

* clean log_loss

* Move bilinear_tensor_product from fluid to static

* Fix unitests when remove log_loss

* Fix bug when move bilinear_tensor_product

* fix test_fleet_nocvm_1.py

* Add bilinear_tensor_product into all list

* Fix code style

* Fix comments in bilinear_tensor_product

* Fix comments in bilinear_tensor_product

* Fix comments

* isort all files

* revert conflicting files

* revert conflicting files

* revert conflicting files

* revert conflicting files

* revert conflicting files

* update config

* re-blacken python code

* temporarily disable date and diff_py_file

* skip a format

* [CodeStyle] remove all future import

* revert test_error.py

* restore future import in example code

* 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

* test=develop, rm netifaces

* add unittest for paddlerolemaker with gloo

Integrated Trainer of Parameter Server (API add `fluid.contrib.layers.sparse_embedding` only) (#22957)

* Integrated Trainer of Parameter Server

* add mock barrier all
test=develop

* fix
test=develop

* fix
test=develop

* fix
test=develop

* add timeout and http store in communication, add revert and confirm in fleet
* test=develop

* add unit accessor in fleet, support DownpourUnitAccessor
* test=develop

* add save with prefix
* test=develop

* fix no cvm, when accessor is DownpourSparseValueAccessor, set no_cvm=True
* test=develop

* add clear_one_table
* test=develop

* add GeneralRoleMaker which is for general usage
* test=develop

* fix PaddleCloud Role maker & add warning in distribute transpiler  & change rpc_retry_times

* optimize cloud rolemaker, test=develop