* 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

* Migrate Dim and DDim from paddle::framework into pten namespace

* fix paddle::framework::Array

* fix framework::Array

* replace and remove complex64/128 types in custom OP and other files

* fix custom_tensor_test fail bug

* fix custom_conj_test fail bug

* fix dispatch_test_op build fail bug

* modify conj, real, imag OP to complex template

* replace with complex template to dot Op

* replace with complex template to Abs Op

* add support for complex64 and complex128

* add abs test case

* use std::abs to fix abs bug

* fix the abs bug

* fix abs bug

* rewrite abs op

* rewrite abs op and remove abs in activation

* remove abs register in old codes

* fix abs_grad type error

* fix abs double_grad output name error

* modify abs_grad, abs_grad_grad functor for windows building

* format code style

* fix the bug of result is nan when the divisor is zero

* add missing abs attr and add abs for float16

* dot op support complex types

* matmul support complex types

* add test case

* matmul broadcast gradient support complex

* move conjFunctor to complex_functor.h

* add complex real op & api & unittest

* add imag op & api & unittest

* refactor op impl

* revert simplify writing due to complile failed

* polish details

* polish grad op code