[MLIR][Math] Add support for f16 in the expansion of math.roundeven

Add support for f16 in the expansion of math.roundeven.
Associated GitHub issue: https://github.com/openxla/iree/issues/13522
This version addresses the build issues on Windows reported on
https://reviews.llvm.org/D157204

Test plan: ninja check-mlir check-all

Differential revision: https://reviews.llvm.org/D158234