* replace part of the old implementation, test=develop

* restore concat op, test=develop

* update all ops implemention & delete GetDataTypeOfVar func, test=develop

* no longer need to define all embedding layers (no one less) of all slots in each program. make trainer_param repeated in ps.proto.
* add find_distributed_lookup_table_grads instead of hard code GRAD
* support embedding stop gradient. push sparse has error before fix this.* 
* fix fill sparse, skip slots which do not have embedding. each slot's embedding in a sparse table should be used in all training programs before fix this.
* fix pull sparse, skip slots which do not have embedding.
* fix collect feasign label info, skip slots which do not have embedding.
* support when there are multi sparse tables in one or multi training programs, each program can pull/push its own related sparse tables instead of all sparse tables.
* test=develop

test=develop

consider the situation that shape of input can contain more than one -1.
test=develop

* Make formatted ENFORCE stack adapt to more situations and polish details, test=develop

* restore template message position, test=develop

* All elements in attr(shape) of crop_tensor can be -1, test=develop, test=document_preview

* fix the bug that attr(offsets) should be initialized, test=develop

* test=develop

* test=develop

* test=develop

* test=develop

* add more err msg, test=develop

* add more unittests, test=develop

* make search_compute support avx only

* clean search_compute.h

* rename sse_axpy to avx_axpy

test=develop

* update CMakeLists.txt

test=develop

* add PADDLE_ENFORCE for dygraph to optimize error throw, test=develop

* fix some error, test=develop

* delete PADDLE_ENFORCE_EQ in VarBase::NewVarBase, test=develop

* add op indicate var type method call check

* add error test example, test=develop, test=document_fix

* add count judge, test=develop, test=document_fix

* polish example detail, test=develop, test=document_fix

* test indicate var data type method, test=develop, test=document_fix

* test no get expect kernel type, test=develop, test=document_fix

* remove test case, test=develop test=document_fix

* jit/trace 1st version, test=develop

* add more unittests, test=develop

The op should handle k=1024

test=develop
Signed-off-by: Nzhaoyuchen <zhaoyuchen01@baidu.com>

* refine Categorical and MultivariateNormalDiag en doc test=develop, test=document_fix

* refine Categorical and MultivariateNormalDiag en doc test=develop, test=document_fix

This reverts commit dc229b41.

Bug Fix: Paddle-TRT cannot handle adaptive pooling in pool2d op converter and "num" attribute in split op converter (#20733)

* fix pool2d trt converter, test=develop

* add fix for split op converter, test=develop

* mv sampcd_processor.py to tools

test=develop test=document_fix

* update example script

test=develop test=document_fix

* update the infer shape of matmul,  test=release/1.6

* add unittests of matmul, test=release/1.6

* change func names, test=develop

test=develop

* add support for __get_item__ of Variable test=develop

fix ExecutionContext::HasInput and ExecutionContext::HasOutput depend on the scope structure, test=develop (#20721)