Tpetra::CrsMatrix: Use new KokkosKernels sumInto where possible
Created by: mhoemmen
@trilinos/tpetra See #369 (closed) and #447 (closed). When @bathmatt added sumIntoValuesSorted to KokkosSparse::CrsMatrix, there was some controversy about whether it was adequately tested. The best way to test it (and optimize it) would be to make Tpetra::CrsMatrix use it, where that is possible.
This requires implementing the search "hint" (see #369 (closed) discussion). I'm doing this by changing those methods to call the existing and tested findRelOffset function. Tpetra::Crs{Graph, Matrix} already test this, and the implementation works even if the graph or matrix has never been fill complete.