Support Scalar type as the Disc module input/output type

To enable BladeDISC compilable, the input and output should be Tensor type, It works well in TensorFlow world, but insufficient in PyTorch world, because a considerable number of inputs/outputs is Scalar type as the following illustration:

```yaml
- func: add.Scalar(Tensor self, Scalar other, Scalar alpha=1) -> Tensor
```

A workaround way is that casting it to Tensor outside of Disc cluster and cast back to Scalar inner cluster as the following illustration:

```text
Give:
with prim::FusionGroup(
%1: Scalar,
%2: Scalar):
%3 Tensor = aten::add(%1, %2)
return %3

Execute: CastScalarInputs(sub_graph)

After:
with prim::FusionGroup(
%1.1: Tensor,
%2.1: Tensor):
%4 int = aten::item(%1.1, 1)
%5 int = aten::item(%2.1, 1)
%3 Tensor = aten::add(%4, %5)
return %3
```

Maybe to support Scalar as the input type in Disc is a better way.