Skip launching kernels with zero grid in AOT Inductor (#110312)
Summary: with the grid computed in terms of unbacked `SymInt`s, it can happen that the grid is zero size. This causes CUDA error on `cuLaunchKernel` in the AOT Inductor codegen.
In this PR, when the grid contains unbacked `SymInt`s, a check is added around the `launchKernel` in the AOT Inductor's C++ wrapper codegen to make sure that the grid is not zero-size.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/110312
Approved by: https://github.com/chenyang78
