test=release/1.7

* support slice double grad, test=develop
* merge two doublegradopmaker to one doublegradopmaker,test=develop
* change the shape of slice_OP's unittest, test=develop

* test=develop, bug fix for trainer_factory (#22751)

* test=develop, optimize distributedstrategy (#22677)

* add recorded cuda memory apis, fix typo, test=develop

* add more ut, test=develop

* follow comments, test=release/1.7

* fix py35 incompatible issues, test=release/1.7

* add sync communicator and implement

delete redundant information.

test=release/1.7 test=document_fix

* Add TopK Op Grad CPU&GPU Kernel test=develop

* Add TopK Op Grad, modify grad op maker test=develop

* Add TopK Op Grad, modify grad op maker test=develop

* Add TopK Op Grad, modify PADDLE_ENFORCE test=develop

* Add TopK Op Grad, modify PADDLE_THROW test=develop

* Add TopK Op Grad, modify unittest test=develop

* fix ngraph top k op unittest test=develop

test=release/1.7, test=develop

* update

* update test=develop

* update compile set test=develop

* update compile set test=develop

* update test=develop

* update test=develop

* update test=develop

* update compile setting test=develop

* update compile setting test=develop

* update run demo test=develop

* update test=develop

* update test=develop

* fix test=develop

* update test=develop

* update test=develop

* update test=develop

* update test=develop

* update test=develop

* update test=develop

* update test=develop

* update test=develop

* update test=develop

* update format test=develop

* update format test=develop

* update style test=develop

* update style test=develop

* change style test=develop

* change style test=develop

* change style test=develop

* add dataset unittest test=develop

* update test=develop

* update for record test=develop

* udpate style for record test=develop

* update for record test=develop

* update for record test=develop

* update for record test=develop

* fix format test=develop

* update test=develop

* update test=develop

* update test=develop

* update test=develop

* update test=develop

cherry-pick #22615

* optimizer var exlcude fluid.data var. test=develop

* fix compute priority. test=develop

* cherry-pick #22555
test=release/1.7, test=develop

* cherry-pick #22621
test=release/1.7, test=develop

pretty print for communicator flag

* add deprecated for distribute transpiler, will delete it after 2.0.0, test=develop

* enhance load program state; test=develop

* optimize commet; test=develop

* split unittests in data loader test, test=release/1.7

* split unittests to different files, test=release/1.7

* remove repeat unittest, test=release/1.7

Post_training_quantization support set quant 8/16 bits 

* 1. load model from memory

2. scale is no longer added when saving inference model

test=develop

* raise ci coverage, test=develop

* supports saving weights to memory. test=develop

* raise ci coverage, test=develop

* fix PADDLE_ENFORCE messages, test=develop

* Add support for dynamic_decode(while) training. test=develop

* Fix assign_op and tensor_array_read_write_op after solving conflict. test=develop

* Fix test_rnn_decode_api.py. test=develop

* Refine docs for apis in rnn.py. test=develop

* Adjust outputs of dynamic_decode. test=develop

* Remove the force_cpu update in assign_op. test=develop

* Remove the force_cpu update in assign_op. test=develop

* Make RNNCell.get_initial_states support batch_dim_idx argument. test=develop

* Rename _create_array_outof_while as _create_array_out_of_while in rnn.py.

test=release/1.7

* add thread barrier for the compiled program

* Introduce Ernie NLP

* Fix error regarding incorrect attr type

test=release/1.7
Co-authored-by: NWojciech Uss <wojciech.uss@intel.com>

This PR makes assign op support LoDTensorArray and enable the loop_vars in
while_loop to support tuple or list.