* [CustomDevice] add custom device api

* update

* update

* test=document_fix

* update

* update

* add  examples

* [PluggableDevice]custom kernel to pten core structs

* mod extension.h for custom op

* compatible python for CI

* support custom context

* refactor to pten

* fix windows and ut

* 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