* save/load in ps runtime(the_one_ps) (#36097)

* add trainer desc config to distributed strategy

* code style modified

* data_feed set lod

* fix bug

* code style

* fix bug

* save load

* save load

* save unittest

* add unittest of the_one_ps

* unittest

* add todo in communicator sendsparse

* fix bug in save_inference_model (#37362)

* oneps (3/4)
Co-authored-by: NMrChengmo <cmchengmo@163.com>
Co-authored-by: Nmalin10 <malin10@baidu.com>
Co-authored-by: Nchengmo <chengmo@baidu.com>

* add size method for large scale

* add large scale UT

* add ut for checkpoint

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

* Integrated Trainer of Parameter Server

* add sync communicator and implement

* test=develop, fix geo Send & Init

* add half_async in the communicator
* fix DistributedStrategy

* add distributed_strategy

* refector geo sgd & communicator

* add is_runnning in communicator, test=develop

Async exe support communicator