[ValueTracking] Add support for `xor`/`disjoint or` in `isKnownNonZero`

Handles cases like `X ^ Y == X` / `X disjoint| Y == X`.

Both of these cases have identical logic to the existing `add` case,
so just converting the `add` code to a more general helper.

Proofs: https://alive2.llvm.org/ce/z/Htm7pe

Closes #87706