e25db2f6b3
More closely match improveShuffleKindFromMask's shuffle ordering by trying to match a SK_InsertSubvector shuffles patterns before SK_Select - both can match many of the same patterns, but its much easier to recognise when a SK_InsertSubvector can be converted to SK_Select than vice-versa. Another step towards #145335 - which I'm hoping will allow us to generalise improveShuffleKindFromMask and remove getInstructionCost's shuffle matching entirely.