* [Dy2St]Renae in_declarative_mode into in_to_static_mode

[Dy2St]Renae in_declarative_mode into in_to_static_mode

fix comment

* rename fluid to base

* fix setup and rename paddle.fluid

* fix protobuf generated paddle.fluid

* fix some errors

* fix cmake depends

* fix some error

* try to fix cache error

* fix codestyle && some doc error

* remove build change

* fix some error

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Co-authored-by: NXiangGao <jeff41404@gmail.com>