[AArch64][GlobalISel] Add support for some across-vector NEON intrinsics

Support uaddv, saddv, umaxv, smaxv, uminv, sminv, fmaxv, fminv,
fmaxnmv, fminnmv intrinsics in GlobalISel.

GlobalISelEmitter couldn't import SelectionDAG patterns containing nodes
with 8-bit result type, since they had untyped values. Therefore,
register type for FPR8 is set to i8 to eliminate untyped nodes in these
patterns.

Differential Revision: https://reviews.llvm.org/D146531