* 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

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

* fix bmm bug

* bmm style

* fix bmm

* add gradient check to reduce ops

* add skip gradient check to reduce ops test=develop

* modify stack api test=develop

* add bmm op and move serval ops from fluid.layers to tensor test=develop