[mlir][NFC] Add helper for common pattern of replaceAllUsesExcept

This covers the extremely common case of replacing all uses of a Value
with a new op that is itself a user of the original Value.

This should also be a little bit more efficient than the
`SmallPtrSet<Operation *, 1>{op}` idiom that was being used before.

Differential Revision: https://reviews.llvm.org/D102373