[PyTorch] Fix many Tuple::elements() callsites (#64065)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/64065
It is only safe to mutate Tuple elements if you are the sole owner
of the tuple. The most efficient way to do this, then, is
`std::move(*std::move(tupleIValue).toTuple()).elements()` (the
innermost move allows `IValue::toTuple()` to avoid a refcount bump and
the outermost move allows the element vector to be moved out of the
tuple), but many callsites write simply
`tupleIValue.toTuple().elements()`, which incurs many extra refcount
bumps.
ghstack-source-id: 139468088
Test Plan: CI
Reviewed By: ezyang
Differential Revision: D30592621
fbshipit-source-id: e8312de866de09b9ea2a62e5128cbf403ee16f09
