[Phi]Separate AddKernel/DivideKernel/SubtractKernel/MultiplyKernel from ElementwiseKernel（Part1） (#41806)

* seperate add/div/sub/mul from elementwise

* delete code

* fix compile bugs

* deal with conflict

* fix bugs when compile

* fix windows unit test bug

* fix ci converage bugs

* [DoubleGrad] Enabled double grad test cases in eager_mode for test_imperative_double_grad

* Fixed elementwise issue

* Addressed CI failures

Revert "Revert "[Phi] Move elementwise_floordiv and elementwise_pow to phi (#40993)" (#41065)" (#41110)

This reverts commit 3a6f1135.

This reverts commit b532315d.

* mv floordiv to phi

* mv elementwise_pow to phi

* fix as review

* move elementwise_div grad

* change mutable_data to alloc

* fix compile bugs

* 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

[Pten]Refactor elementwise_add grad / double grad / triple grad Kernel and move them to pten (#39048)

* refactor elementwise add grad

* fix compile bugs

* fix unit test bugs

* fix file conflicts

* fix bugs when buildPtenContext