More extensible layout for cholesky

[dannys4]

Currently, the cholesky requires you to have LayoutLeft for the sake of CUBLAS requiring it. This is somewhat irritating because the OpenMP backend of kokkos has a default layout of LayoutRight, so when I sample with the Gaussian distribution, I have to call the SampleImpl function directly, lest I want to get a runtime error that says I'm trying to use an incompatible LayoutRight View (i.e. I can't use the default Layout for Views when interacting with the Cholesky, namely within the Gaussian distribution).