* move unbind to phi

* revert infer shape

* add header file

* move concat_and_split to phi

* 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 blas related files
* move lapack related files

* clean useless header in pten core

* fix compiled failed

* fix cmake target

* fix typo

* resolve conflict

* move operators/math/math_function_* to pten/kernels/func
* namespace from `paddle::operators::math` to `pten::funcs`

* remove hybird dir

* resolve conflit

* change 'math' to 'math_kernel'

* fix compile bugs

* merge develop

* fix compile bugs

* move cpu_impl of elementwise kernel to new directory

* rename cuda to gpu

* revert CMake change

* resolve conflit

* rename other cuda to gpu

* poish details

* unify device context entrance

* move all_context include to header

* polish cmake relay for device_context

* fix npu compile failed

* fix npu compile failed

* add pten reduce kernel

* add reduce_sum kernel

* update attribute args and order

* make out dtype undefined

* fix empty input error

* merge develop branch

* rename sum as reduce function

* rename sum as reduce function

* fix reducekernelImpl args error

* add reduce cuda kernel

* modify dims type to const &

* remove unsed log

* fix reduce_all out eigen function error

* remove unused codes

* add the missing sum api define and testcase

* merge develop branch

* fix sum test axis value error

* replace pten mean kernel with reduce_mean

* revcover meam cuda to original implement