Macro impl_fixed_convert_unsigned

macro_rules! impl_fixed_convert_unsigned {
    ($($t:ty),* => $fixed:ty) => { ... };
}

Implements IntegerToFixed conversion for all unsigned integer types in the list.

• to_fixed: Converts the integer into the corresponding fixed-point type using saturating conversion to prevent overflow.
• from_fixed: Converts back from fixed-point to the integer, clamping values to the integer’s max if the fixed-point inner value exceeds it.

Usage: impl_fixed_convert_unsigned!(u8, u16, u32 => FixedU64);