[llvm] Reland "[ValueTracking] Compute knownbits from known fp classes" (PR #92084)

[via llvm-commits]

dyung wrote:

Hi @dtcxzyw, one of our internal tests started failing and I bisected it back to this change you made. I have put the repro in #92217, can you take a look?

https://github.com/llvm/llvm-project/pull/92084