* merge legacy to fluid

* Remove legacy code

* Remove legacy code

* Remove DataType test

* Using Tensor directly instead of using EagerTensor

* support gradient_accumulation

* make test_imperative_lod_tensor_to_selected_rows longer

* make test_imperative_lod_tensor_to_selected_rows longer

* Support allocate_from in Tensor and allocate_data in Context

* fix #ifdef CUDA

* fix cycle depends

* fix test_xxx_dev_api failed

* fix windows compiling error

* fix unittest

* modify into PImpl

* fix selected rows

* add TODO comment

* refine interface according reviewer

* Added selected_rows and rw_lock to pten

* Renamed the unit test target to fix CI

* Removed Class SelectedRows in Fluid, changed include/cmake relationship, use pten::SelectedRows in Fluid

* Remove rw_lock.h,rw_lock_test.cc in fluid

* Use pten::RWLock and pten::AutoRDLock, fix CI

* Use pten::SelectedRows

* Use pten::SelectedRows

* Fix to pass NPU CI

* Selected_Rows inherits from TensorBase

* Use pten::SelectedRows, to pass NPU CI

* To fix NPU CI

* To fix NPU CI again

* Use paddle/pten/core/enforce and polish code

* Renamed selected_rows.* -> selected_rows_utils.*

* Added selected_rows and rw_lock to pten

* Removed useless header

* Renamed the unit test target to fix CI

* Use pten::framework::DDim

* Set selceted_rows_test properties timeout

* Polish code to pten style
Co-authored-by: NChen Weihang <chenweihang@baidu.com>

* Merged LoDTensor with Tensor,test=allcases

* Patched python level LoDTensor

* Patched python level LoDTensor

* Merge Tensor into DenseTensor

* Fixed namespace issues,test=allcases

* Fixed merge issues

* Fixed inference issues

* Fixed NPU test issues

* Fixed merge issues

* add pten::Place data structure.

* update ci problem

* fix ci problem

* update

* using platform::Place=pten::Place

* remove BOOST_GET_CONST for CPUPlace and GPUPlace

* compile pass 25%.

* compile pass 45%

* compile pass 60%

* remove boost_get for xpu npu mlu and ipu

* compile pass on cpu and gpu.

* fix compile problem

* fix compile error.

* update

* fix ci problem

* update

* ci approve

* fix ci problem

* fix ci eager test problem

* remove BOOST_GET_CONST

* fix npu compile

* support state_dict save to memory.

* Perfect unittest

* perfect unittest.

* suport saving binary var to memory

* polish code.

* packag save/load files into pybind/io.py

* polish code .

* add example for save to memory; remove useless save load function(_load_static_dict,_save_dygraph_dict)

* delete _load_static/dygraph_dict;_save_static/dygraph_dict

* edit example of paddle.save/load

* support save/load binary format tensor

* Fix error when create cudaplace

* Fix error when create cudaplace

* Fix error when create cudaplace

* get devive context from pool.

* move define of 'SerializeToStream' and 'DeserializeFromStream' to 'lod_tensor.cc' and 'selected_rows.cc'.

* improve coverage.

* improve coverage.

* polish API

* deal with conflict

* disable save/load large file in unnittest

* split unnittest.

* use iwyu clean include, test=develop, test=win

* compilation error, test=develop

* fix compilation error2, test=develop

* fix compilation error3, test=develop

* fix compilation error4, test=develop

* fix compilation error5, test=develop

* fix compilation error6, test=develop

* fix compilation error7, test=develop

* fix compilation error8, test=develop

* fix compilation error8, test=develop

* fix compilation error10, test=develop

* fix compilation error11, test=develop

* polish framework error message part 7

* fix typo

* polish by reviewes comment

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

* Integrated Trainer of Parameter Server

test=develop

Optimize selected rows for dist lookup table with rwlock