[llvm] Add ShuffleVectorInst. (PR #104891)

[Jorge Gorbe Moya via llvm-commits]

slackito wrote:

Apologies for the large PR. `ShuffleVectorInst` has a ton of methods and, given that the changes are mostly mechanical because they're just wrappers of the underlying LLVM class, I decided to put them all into a self-contained PR instead of finding some artificial splitting point.

https://github.com/llvm/llvm-project/pull/104891