Fix scalar type resolution for optional tensor (#94427)
When TorchScript Value has an optional tensor, `dtype()` or `scalarType()` is not available and raise (by design).
The symbolic `_op_with_optional_float_cast` must check whether the tensor is otpional or not before calling the scalar type resolution API. This PR fixes that
Pull Request resolved: https://github.com/pytorch/pytorch/pull/94427
Approved by: https://github.com/abock, https://github.com/shubhambhokare1
