Support NaN and ±Infinity for C++ ⇔GeoJSON synthetics

[nyurik]

In order to have comprehensive testing, we must ensure every possible value we support is readable in every implementation. GeoJSON does not support non-numeric floats, which means we should serialize it as strings to make sure we are consistent in every language. I used Rust names for the values, I hope we don't start a holy naming war here :). f32 and f64 are needed to be explicit about the originating data type.

Requirements

• Serialize f32::NAN → "f32::NAN"
• Serialize f32::INFINITY → "f32::INFINITY"
• Serialize f32::NEG_INFINITY → "f32::NEG_INFINITY"
• Serialize f64::NAN → "f64::NAN"
• Serialize f64::INFINITY → "f64::INFINITY"
• Serialize f64::NEG_INFINITY → "f64::NEG_INFINITY"

@TimSylvester

[HarelM]

I think this was also solved by the following PR:

• chore(ts, cpp): share code between ts and cpp for synthetic tests #1035

As C++ and typescript share the same comparison code.
@louwers can you make sure and close this issue if this is the case?