* first commit

* 2nd commit

* unify complex type trait and fix real imag bug

* add unittest for type tratis

* Optimize the where_op by the elementwise_op funtion

* Modified where_op & abs_grad_op by elementwise interface

* rename pten dir to phi

* rename namespace to phi

* rename infrt pten dir to phi

* resolve conflict

* rename pten to phi in cmake

* revert all infrt change

* change needed files

* fix infrt failed

* fix inference failed

* move complex_functors.h and update all references to symbols within it

* Move Abs op to pten

* Fix NPU compilation error

* Fix CI error

* Use LaunchSameDimsElementwiseCudaKernel in pten