[llvm] [WebAssembly, llvm] Add llvm.wasm.ref.test.func intrinsic (PR #147486)

[Hood Chatham via llvm-commits]

hoodmane wrote:

Hmm one test failed:
```
FAIL: Flang :: Lower/OpenMP/unroll-heuristic02.f90 (1524 of 3614)
```
It seems unrelated to my changes so probably a flake?


https://github.com/llvm/llvm-project/pull/147486