Provide a fast path for constructing a `StridedMemoryView` from a `cupy.ndarray`

[leofang]

[leofang]

I have in mind:

host:

arr = cp.empty(...) 
...
view = StridedMemotyView(arr, s=-1)
launch(stream, config, kernel, view.as_mdspan())

device:

template <typename T>
__global__ void kernel(cuda::std::mdspan<T, ...> a) {
  ...
}