kokkos: add serial backend explicitly. add kokkos options and kokkos cuda options. (#9276)
kokkos: add serial backend explicitly. add kokkos options and kokkos cuda options. (#9276)


iulian787/spack,iulian787/spack,iulian787/spack,iulian787/spack,LLNL/spack,LLNL/spack,LLNL/spack,LLNL/spack,LLNL/spack,iulian787/spack