[AArch64] Expand the SVE min/max reduction costs to NEON

This takes the existing SVE costing for the various min/max reduction
intrinsics and expands it to NEON, where I believe it applies equally
well.

In the process it changes the lowering to use min/max cost, as opposed
to summing up the cost of ICmp+Select.

Differential Revision: https://reviews.llvm.org/D106239