`mdspan_to_view` needs to support transposed layout

[fnrizzi]

[mhoemmen]

There are a few different options. The easiest thing might be just to write a Kokkos::View adapter for arbitrary mdspan layouts (and accessors!). It could just wrap the mdspan (storing it by value) and defer to its array access operator(). That would solve the problem generally. You could then specialize for specific layouts or accessors if performance warrants the effort.