[X86][AVX] Use lowerShuffleAsLanePermuteAndSHUFP to lower binary v4f64 shuffles.

Only perform this if we are shuffling lower and upper lane elements across the lanes (otherwise splitting to lower xmm shuffles would be better).

This is a regression if we shuffle build_vectors due to getVectorShuffle canonicalizing 'blend of splat' build vectors, for now I've set this not to shuffle build_vector nodes at all to avoid this.