* adjust test_elementwise_sub's tolerance, max_relative_error of grad and
atol/rtol of output to 1e-3

* fix the dtype in setUp

* fix the elementwise_sub optest

* modify elementwise_sub optest

* fix and add bf16/fp16 to elementwise_sub

* fix elementwise_sub bugs

* fix bugs

* fix elementwise_sub op

* fix the data type

* fix elementwise_sub

* fix elementwise

* fix elementwise_sub

* fix bugs

* fix elementwise sub

* fix elementwise_sub

* remove scalar and vector