* move reduce kernels into one file

* rename reduce_prod to prod

* move reduce sum/mean from math_kernel into reduce_kernel

* rm comment

* move elementwise function to funcs directory

* fix compile bugs

* modify according to comment

* add ele_add

* add ele_mul

* add ele_sub

* sovle conflict

* fix npu

* refine ele_add

* add ele_mul unittest

* refine ele_sub

* refine ci

* refine unittest

* unify register macro

* rename declare macro

* fix infrt error

* 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

* add more op int16 support

* fix xpu ci

* clean useless header in pten core

* fix compiled failed

* fix cmake target

* fix typo

* resolve conflict

* Support allocate_from in Tensor and allocate_data in Context

* fix #ifdef CUDA

* fix cycle depends

* fix test_xxx_dev_api failed

* fix windows compiling error

* fix unittest

* modify into PImpl

* fix selected rows

* add TODO comment

* refine interface according reviewer

* updates callers, test=develop

* updates tensor, test=develop

* fixes errors, test=develop

* remove some dtypes, test=develop

* fix errors in the base storage modification, test=develop

* fixes a bug, test=develop

* fixes the bugs in push the whole, test=develop

* updates, test=develop

* update

* update, test=develop

* fixes the mac-py3 CI, test=develop

* remove the storage impl, test=develop

* updates some codes, test=develop

* update, test=develop

* updates pten allocation, test=develop

* add kernel for c++ api

* fix compile bugs

* fix kunlun compile bugs

* perfect cmake

* fix compile bugs when run ci-inference

* fix compile bugs

* add non-raw kernel for fluid op

* fix compile bugs

* fix compile bugs

* fix unit test bug

* Migrate bfloat16/float16/complex from platform into pten::common

* fix typo

* fix code style

* rename register marco

* fix error changing

* fix format error

* move eigen/reduce.h imple into cpu/reduce.h

* ctx to dev_ctx

* move gpu_impl of elementwise kernel

* change copyright to 2022

* change 'math' to 'math_kernel'

* fix compile bugs

* merge develop

* fix compile bugs

* fix compile bugs

* move reduce files by new rule

* add set header

* format code style

* merge develop and fix conflict

* merge develop and fix conflict
Co-authored-by: NYuanRisheng <yuanrisheng@baidu.com>

* change 'math' to 'math_kernel'

* fix compile bugs

* merge develop

* fix compile bugs

* move cpu_impl of elementwise kernel to new directory

* change 'math' to 'math_kernel'

* fix compile bugs

* merge develop

* fix compile bugs