* 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

* move clip op to phi

* fix as review

* update hierarchical_sigmoid_kernel.cc

* update selected_rows

* update clip_kernel.cu

* fix as review

* [Phi] Migrate Adam and Adamw into Phi

* fix compile error and unittest ok

* fix compile error and unittest ok

* fix undefined reference to fLI::FLAGS

* test depend on operator

* fix cmake

* fix xpu compile

* fix infrt

* fix amp_type_traits

* fix amp_type_traits

* modify according reviewer

* modify according reviewer

* fix dtype float16

* fix typo

* fix Cmake

* fix code style