[clang] [llvm] [LLVM] Add IRNormalizer Pass (PR #68176)

[Justin Fargnoli via cfe-commits]

justinfargnoli wrote:

@vvereschaka, I agree. 

Note: The problem is that `IRNormalizer` produces a change that invalidates an analysis. It's not that IRNormalizer should declare that it's not preserving an analysis. 

I likely won't be able to fix this for a few days. @vvereschaka, should I revert 1295d2e6da2fe90f3b770ab1d35bf5caecd38bed in the meantime? 

https://github.com/llvm/llvm-project/pull/68176