* refactor the optional tensor

* remove optiona<MetaTensor> in InferMeta

* fix bug

* fix optional<vector<Tensor>>

* fix bug

* fix rmsprop

* fix amp of eager_gen

* polish code

* fix deleted code

* fix merge conflict

* polish code

* remove is_nullopt_

* fix merge conflict

* fix merge conflict

* add graph_send_recv yaml

* deal with confict

* fix compile bugs

* add out_size shape for graph_send_recv

* fix bug in register kernel: no const int& support

* add out_size in infermeta

* change unittest

* fix unittest

* fix out_size default value

* fix doc

* delete arg mapping

* add sig

* move -1 to 0

* move -1 to 0

* [Phi] transfer old kernel to pten kernel for the graph_send_recv op

* update the code for the define of graph_send_recv

* fix the gradient problem for graph_send_recv

* fix the compile problem

* update the enfore message for the windows

* update the code for the compiler

* update compiler problem for the windows

* udpate the code for windows

* fix some format problem