[llvm] [SandboxIR] Implemented isVolatile() for LoadInst (PR #100717)

[via llvm-commits]

vporpo wrote:

Now that we can check `isVolatile()` we can also add a new `LoadInst::create()` function with a `bool isVolatile` argument. But this can be a separate PR.

https://github.com/llvm/llvm-project/pull/100717