* removing dependent to fluid/framework/eigen.h in phi

* more fix according to PR-CI-Py3 fail

* 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 segment_pool to phi.

* mark summed ids as optional tensor.

* fix as reviews.