[llvm] [VectorCombine] Add foldShuffleOfIntrinsics. (PR #106502)

[David Green via llvm-commits]

davemgreen wrote:

Could you use isTriviallyVectorizable to detect the instrinsic, with the related isVectorIntrinsicWithScalarOpAtArg/isVectorIntrinsicWithOverloadTypeAtArg routines to rule out the more difficult cases?

https://github.com/llvm/llvm-project/pull/106502