Do not use ZeroTensor for inplace ops (#69998)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/69998
Fixes: https://github.com/pytorch/pytorch/issues/69855
The check for undefined grads for forward AD was not being run because `check_undefined_grads` was only passed as True by OpInfo for backward AD. This PR updates gradcheck to interpret `check_undefined_grads` as possibly for forward or backward AD.
This PR also updates codegen to 1) not use ZeroTensor for `self` when the op is inplace. 2) only create zeros (either through ZeroTensor or at::zeros) if the tensor itself is not undefined. Previously we would error in this case when we call `.options` on the undefined tensor.
~TODO: undo the skips that are due to the original issue~
Test Plan: Imported from OSS
Reviewed By: bdhirsh
Differential Revision: D33235973
Pulled By: soulitzer
fbshipit-source-id: 5769b6d6ca123b2bed31dc2bc6bc8e4701581891
