* add tensor clone

* fix unittest test_var_base

1. support channel last in BatchNorm*d (#27875)
2. fix a bug in batch_norm_op cuda kernel by extracting ResizeToChannelFist(Last), TransToChannelFirst(Last) to operators/layer_utils.h

* support setting xpu place

* add ut, test=kunlun

* fix adam

* fix gpu adam

* fix code style

* fix ut

* update ut add cuda code

* add stack pool2d roi_align xpu op,test=kunlun

* error message opt, test=kunlun

* add xpu unittest,test=kunlun

* skip check grad,test=kunlun

* fix boostget , test=kunlun

Add elementwise XPU OP kernel for KUNLUN core, including (but still cannot process common broadcast

* add sparse tensor load method

update the code for the topk message optimize 

* polish some error message

* add white list

* revert shell script change

* test=develop, bug fix for parameter_recv
* test=develop, for unittest, test_fleet_rolemaker_new

*test=kunlun

* add multitask

* add multitask, test=develop

* fix code style, test=develop

* add partail push dense, test=develop

* fix has_kay in py3, test=develop

* fix, test=develop

* fix, test=develop

* fix, test=develop

* fix norm api doc, test=develop

* fix error message, test=develop

* fix api norm, test=develop

* add adagrad, test=develop

* fix bug, test=develop

* fix bug, test=develop

* add spetral_norm, test=develop

* fix adagrad, test=develop

* merge , test=develop

* add lookup_table_v2_op_xpu, test=kunlun

* add lookup_table_v2_op_xpu, test=kunlun

* change some Tips ,test=kunlun

* use exhaustive_search for float16

* tune algo only when dtype is float16

* add dropout,log_loss, test=kunlun
* fix dropout, test=kunlun
* polish error message, test=kunlun
* change boost::get to BOOST_GET_CONST, test=kunlun
* fix copyright, test=kunlun

* support mean,softmax_with_cross_entropy on Baidu Kunlun,test=kunlun

* fix unittests error,test=kunlun

* delete boost::get,test=kunlun

* add xpu sgd & momentum

* add conv for xpu, test=kunlun

* polish error_message, test=kunlun

* polish error_message, test=kunlun

* fix copyrigth, test=kunlun

* add xpu slice op
test=xpu

* add slice xpu op
test=xpu

* code style
test=kunlun

* style
test=kunlun

* format
test=kunlun

* op error info

* style

* code format

* add gather_op xpu, test=develop, test=kunlun

* fix ut, test=develop, test=kunlun

* fix the ut,test=develop, test=kunlun

test=develop

* add load_op_xpu for Baidu Kunlun, test=kunlun

* add is_compiled_with_xpu for unit test, test=kunlun

* add is_compiled_with_xpu for unit test, test=kunlun

* use IndexList to improve performance, test=develop

* remove EIGEN_HAS_INDEX_LIST, test=develop

* use IndexList only when EIGEN_HAS_INDEX_LIST is true

* add flattern weight of lstm

* error message optimization in softmax_with_cross_entropy_op

* fix some unsuited comment

* Add double grad in Squeeze and Unsqueeze

* Add double grad in Squeeze and Unsqueeze

Add xpu kernel for KUNLUN core:

* accuracy op
* sign op
* scale op
* sum op

Add default atol in xpu unittest.

* Add test attribute in channelwise_quant op, test=develop

* add matmul doublegrad op

* fix compile errors

* modify code according to review

* delete float16