* change the output format of C++ backward api

* fix merge conflict

* fix sparse api code auto-gen

* fix eager_gen bug

* fix bug of output is null

* fix bug of conv2d_grad_impl

* fix optional grad

* fix bug of eager-gen double_grad

* fix bug

* fix multiply_double_grad bug

* remove node pruning

submanifold convolution

* remove needless deps in unittests

* add gpu marco

* fix other unittests

* fix kernel name error

* fix test_prepare_op

* fix failed dygraph unittests

* fix gpu failed tests

* fix cinn test failed

* fix cinn test failed

* fix dropout tests

* suppport sparse api in yaml

* support auto-gen code of sparse api

* do some refactor

* add unittest test_sparse_conv_api

* add unitest file
Co-authored-by: Nzkh2016 <zhangkaihuo@baidu.com>