[X86] LowerMINMAX - split v4i64 types on AVX1 targets (Issue #55648)

Originally we tried to use default expansion for v4i64 types to make it easier to concatenate the results back together, but this can cause infinite loop issues with existing VSELECT splitting code in narrowExtractedVectorSelect if we have other uses of the VSELECT results (e.g. reduction patterns).

To fix the infinite loop, this patch always splits MIN/MAX v4i64 nodes during lowering and I've added a TODO for combineConcatVectorOps to investigate when we can cheaply concatenate VSELECT/BLENDV nodes together.

Fixes #55648 - regression test case will be added in a follow up.