support types in @non_differentiable

[oxinabox]

Follow up from #212
it doesn't seem to work write with types.
e.g. @non_differentiable Channel(Any, Any)
at least it doesn't seem to work right an play nice with Zygote.

I know one thing that needs to be changes is to use Core.Typeof($primal_name) rather typeof($primal_name) in the signatio.
because Core.typeof(Channel) is Type{Channel} where as typeof(Channel) is DataType (for others it would be a UnionAll I think)
buit I don't think that is the only thing that prevents it working nice with Zygote.