dzn: Enable a couple more caps/extensions

Someone asked me if we supported the shader model 6.4 packed dot product intrinsics, and the answer was no but it looked easy. I realized that'd mean touching the nir_shader_compiler_options in 3 places, so I did some refactoring to pass the relevant parameters to the options getter. On the way there, I realized we didn't turn on i64/f64 in Dozen, so turn that on too.

This found a couple WARP bugs in i64 wave ops, so those tests are skipped until I get a fixed WARP on NuGet, since it's a long fail list.

It doesn't look like DXIL specifies saturating behavior for the packed add intrinsics, so at least for now I'm splitting out the accumulator into a separate saturating add. I'm still assuming that the packed dot product should be considered "accelerated" even if the saturating add part of it isn't.