This PR allows the expand op converter to consider the NoNaN fastmath
attribute to disable the runtime checks for NaNs in E8M0 types. Default
behaviour is still the same.
The OCP document provides all-ones as NaN for E8M0, but for pre-MX I8
quantization, the checks for NaNs are prohibitively expensive,
especially if the hardware doesn't have native support for that type.
81e0de2ea5