`Val::uses()` may return false uses for scalars

[naoyam]

For tensors, we do a dependency analysis to find expressions that are indeed used to producer fusion outputs. For scalars, that's not the case, but Val::uses() can contain expressions that are outside of the given fusion. This hasn't been an issue, likely because they are just scalars, but it's not consistent either as for tensors they are truly uses in the fusion.

I this this can be fixed by using traverse_members and traverse_attributes options in this getExprs:

https://github.com/NVIDIA/Fuser/blob/main/csrc/fusion.cpp#L586