Reapply "Reapply "[mlir] Add FP software implementation lowering pass: arith-to-apfloat (#166618)" (#167431)"#167436

makslevental merged 4 commits intomainllvm/llvm-project:mainfrom

users/makslevental/fix-againllvm/llvm-project:users/makslevental/fix-againCopy head branch name to clipboard