Fix FFTOffsetViewPair when both Kokkos and FFT are LayoutLeft
Currently, we assume that the layout is LayoutRight when the layouts match for pointer incrementing. This is fine for AccFFT (which always wants LayoutRight), but will cause a problem with heFFTe on a GPU (where both Kokkos and heFFTe will be LayoutLeft). We should have another if statement where we check LayoutRight/LayoutLeft and do the correct pointer incrementing.