This reverts commit 89ad8664.

* refine stack in dygraph mode, test=develop

* update stack, test=develop

* rename Variable to Tensor, test=develop

* add name args to fluid.layers.stack, test=develop

* follow comments

* update doc

* update doc

* follow comments

* add paddle.utils.deprecated.

* add docstring. test=develop

* add alias paddle.utils.deprecated. test=develop

* rm deprecated in python/paddle/fluid/annotations.py. test=develop

* 1. check version before warning. 2. bug fix. test=develop

* bug fix. test=develop

* use paddle.fluid.require_version. test=develop

* fix doc

* fix doc. test=develop

* fix doc. test=develop

* bug fix. test=develop

* use packaging.version. test=develop.

* enhance doc. test=develop

* add compare_version function. test=develop

* add version.py. test=develop

* remove packaging. test=develop

* move compare_version to deprecated.py. test=develop

* remove print. test=develop

* fix. test=develop

* fix. test=develop

* fix. test=develop

* fix. test=develop

* inline. test=develop

* fix. test=develop

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

* Integrated Trainer of Parameter Server

* refine squeeze, test=develop

* update squeeze, test=develop

* refine compile-time infershape, test=develop

* add more unittest, test=develop

* follow comments, test=develop

* add update_api, test=develop

* follow comments, test=develop

* add ci check for changing op-related api without core.ops, test=develop

* generate api_source_md5 file when build, test=develop

* add failed example, test=develop

* add failed example, test=develop

* handle exception, test=develop

* fix doc of logical_* op.

* fix doc of op pow.

* fix comment syntax error9D

* fix operator reciprocal demo.

* fix logical_* ops' doc. test=develop,test=document_fix

* bug fix. test=develop,test=document_fix

* bug fix. test=develop,test=document_fix

* bug fix. test=develop,test=document_fix

* bug fix. test=develop,test=document_fix

* fix bn & in in dy, test=develop

* update instance_norm,test=develop

* fix bugs,test=develop

* add more case in unittest,test=develop

* fix,test=develop

* fix,test=develop

Fix the doc example api for the scale op

* add mish op. test=develop

* Start implementing int8 eltwise add

test=develop

* - Fix to Michal PR

* - Fix

test=develop

* - Lint fixes

test=develop

* - Added checking if elementwise_mul can be used

test=develop

* - Added attribs to skip_attrs_set

test=develop

* - Improved broadcasting

test=develop

- fixes to compilation

- fix

- fix

- Lint fixes

test=develop

* - removed redundant condition

test=develop
Co-authored-by: NMichal Gallus <michal.gallus@intel.com>

* fix bug of prelu when rank not equal 4, test=develop

* fix prelu inference, test=develop

* fix api, test=develop

* fix shape when mode is chennel, test=develop

* remove debug code, test=develop

* add unittest, test=develop

* [dy2stat] Support len

* add convert_call func

* refine code test=develop

* support NHWC in Pool2D, test=develop

* add unittest, test=develop

* fix unittest, test=develop

* fix typo, test=develop

* follow comments, test=develop

* refine comments, test=develop

* test=develop update interpolate & upsample api

* dynamic_gru err_msg enhancement, test=develop

* chunk_eval err_msg enhancement and fix crf_decoding output type, test=develop

* BeamSearchDecoder err msg enhancement, test=develop

* fix doc for chunk_eval, test=develop

* refine lod err msg for chunk_eval, test=develop

* Compatible int32 and int64 for attr in op slice/strided_slice. test=develop

* Polish code in nn.py  test=develop

* Fix bug: set the same dtype for the inputs of elementwise_add. test=develop

* Convert int32 to int64 in slice op to avoid data overflow. test=develop

* Convert int32 to int64 in strided_slice_op to avoid data overflow. test=develop

* improve error reporting message

* test=develop, test=document_fix

* test=develop, test=document_fix
Co-authored-by: Nswtkiwi <1208425345@qq.com>

* fix error message, test=develop

* fix error check of stack and space_to_depth
* test=develop

* Format error message for ops, test=develop

* Fix check in sequence_expand, test=develop

fix check info for flatten hash is_empty op; test=develop

* polish some sl api error message, test=develop

* polish python input check of stride slice, test=develop

* fix unittest bugs, test=develop