pugs

Also change the semantic/implementation of sub-Array and sub-Table
views. One does not use anymore Kokkos' subView which seems to be very
expensive (2 to 3 times the cost for the Lagrangian acoustic solver if
one uses subView for connectivity: lists of sub-items). It looks like
the over cost is related to the memory management (here the reference
counting).

Sub-Array and sub-Table view are coarsely "embedded raw
pointers" (which may not be safe as it is the case in
Kokkos::StaticCrsGraph). However we tried to reduce the risk of having
a view on a destroyed Array/Table by forbidding copy constructors.

ConnectivityMatrix and ItemToItemMatrix still require refactoring. For
instance it would be natural for ItemToItemMatrix  to be replaced by
the appropriate SubItemValuePerValue<ItemId>.