[AArch64][GISel] Add handling for G_VECREDUCE_FMAXIMUM and G_VECREDUCE_FMINIMUM

This is a lot of copy-pasting for the existing handling of
G_VECREDUCE_FMAX/G_VECREDUCE_FMIN to add handling for
G_VECREDUCE_FMAXIMUM/G_VECREDUCE_FMINIMUM in the same way.

Differential Revision: https://reviews.llvm.org/D156615