[llvm] [SandboxIR] Implement missing PHINode functions (PR #101734)

[via llvm-commits]

https://github.com/vporpo commented:

I think we also need a test in `TrackerTest.cpp` (in PHINodeSetters test) to make sure that `replaceIncomingBlockWith()` and `removeIncomingValueIf()` can be reverted properly. They currently call functions that are being tracked, so tracking should work fine, but this may change, and we don't want tracking to fail silently.


https://github.com/llvm/llvm-project/pull/101734