* WIP: start writing combined indexing get

* list/tuple/Variable

* getitem 80%

* add setitem

* add some unittest for setitem

* lazy import

* fix some setitem error

* fix advance indexing with decreasing axes; fix strided_slice input name

* combine int-tensor getitem is ok (without boolean support & broadcast); add getitem unittest for static

* add broadcast & parse bool tensor for __getitem

* [change getitem] _getitem_impl_ to _getitem_static, not deleting the former one

* refine new getitem; fix ut in variable/var_base

* add __getitem__ ut in dygraph

* re-dispatch getitem for Py/CPP; fix strided_slice decrease axes error in dygraph

* fix ut; support tensor in slice

* [change setitem] _setitem_impl_ to _setitem_static, not deleting the former one

* remove some UT (for some, temporarily)

* add IndexError to solve timeout problem in static-mode

* 1.temply forbideen all-False bool-indexput; 2.setitem_static will return new variable

* xpu uses old stratege

* rename dy2st setitem ut to avoid same-name problem

* dy2st for new combined index

* ut case for combine-index with dy2st

* open ut with all-false-bool setitem

* remove useless doc and _getitem_impl_

* change static res

* fix static xpu