Add KVAE 1.0 (#13033)
* add kvae2d
* add kvae3d video
* add docs for kvae2d and kvae3d video
* style fixes
* fix kvae3d docs
* fix normalzation
* fix kvae video for code style
* fix kvae video
* kvae minor fixes
* add gradient ckpting for kvaes
* get rid of inplace ops kvae video
* add tests for KVAEs
* kvae2d normalization style change
* kvaes fix style
* update dummy_pt_objects test for kvaes
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Co-authored-by: YiYi Xu <yixu310@gmail.com>
