[llvm] [AsmParser] Revamp how floating-point literals work in LLVM IR. (PR #190641)

[Jay Foad via llvm-commits]

jayfoad wrote:

Maybe link to https://discourse.llvm.org/t/rfc-floating-point-literals-in-llvm-ir/82974/1 in the description if that's still relevant?

https://github.com/llvm/llvm-project/pull/190641