[Static Runtime] aten::cat out version when it is not being replaced by prim::VarConcat (#64157)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/64157
UseVariadicCat optimization is not applied to aten::cat if list input to the op can not be moved to the position before op (https://fburl.com/diffusion/l6kweimu). For these cases we will need out version for SR.
Test Plan:
Confirm out variant is called:
```
> buck run //caffe2/benchmarks/static_runtime:static_runtime_cpptest -- --v=1
```
Reviewed By: d1jang
Differential Revision: D30598574
fbshipit-source-id: 74cfa8291dc8b5df4aef58adfb1ab2a16f10d90a
