* rename cuda to gpu

* revert CMake change

* resolve conflit

* rename other cuda to gpu

* poish details

* standarded unittest namespace

* fix detail error

* rename to api to copy_to

* support cast method for tensor

* fix compile failed

* adapt to inference api dir for pten

* fix conflit with develop

* fix test_egr_ds_eager_tensor compile failed

* add copy_to and to method for Tensor

* polish msg format

* fix details error

* fix copy_to test compile failed

* fix typo