Support non-contiguous buffers in `SimpleArray::as_span/as_mdspan()`

[yungyuc]

In issue #771 and PR #777, as_span() and as_mdspan() are added to SimpleArray support only C-contiguous memory buffers.

This issue is created to support non-contiguous memory buffer in the as_span/as_mdspan() interface, as mentioned in #777 (review).