[MLIR][arith] More float op folders

Fold `arith.fadd %x, -0.0 -> %x` and similarly for `fsub`, `fmul`, `fdiv`.

Fold `arith.fmin %x, %x -> %x`, `arith.fmin %x, +inf -> %x` and similarly for `fmax`.

Reviewed By: pifon2a, mehdi_amini, bondhugula

Differential Revision: https://reviews.llvm.org/D118244