[llvm] [VectorCombine] Expand `vector_insert` into shufflevector for earlier cost optimizations (#145512) (PR #146479)

[Simon Pilgrim via llvm-commits]

RKSimon wrote:

Thanks - I'm hoping the changes to fmaddsub are heading in the right direction - I originally raised #145512 to help with #144489

https://github.com/llvm/llvm-project/pull/146479