[X86][AVX] lowerShuffleWithPERMV - pad 128/256-bit shuffles on non-VLX targets

Allow non-VLX targets to use 512-bits VPERMV/VPERMV3 for 128/256-bit shuffles.

TBH I'm not sure these targets actually exist in the wild, but we're testing for them and its good test coverage for shuffle lowering/combines across different subvector widths.