[llvm] [WebAssembly] Add pattern for relaxed laneselect (from bitselect simd) (PR #163807)

[Jasmine Tang via llvm-commits]

badumbatish wrote:

hmm, the hand written test case are using `-mattr=+simd128,+relaxed-simd` and thus cannot check if calling `@llvm.wasm.bitselect` can be lowered to bitselect anymore. We probably should update the test case with a different PR

https://github.com/llvm/llvm-project/pull/163807