Remove deprecated usage of public member variables of DualView

[tpadioleau]

see kokkos/kokkos@b027fc2

[yasahi-hpc]

LGTM.
I have minor comments about the index type.
Another point is the usage of assert and throw (not the scope of this PR). In my opinion, we should always throw here since we cannot operate appropriately if conditions are not satisfied.

[tpadioleau]

LGTM. I have minor comments about the index type. Another point is the usage of assert and throw (not the scope of this PR). In my opinion, we should always throw here since we cannot operate appropriately if conditions are not satisfied.

I agree some assert could be transformed into exceptions. I usually prefer to keep assert from low-level functions. For higher level functions where we also want recoverable error reporting, I agree exceptions are better suited.