float is_foo

[jayvdb]

It would be great to have float validators for these:

https://doc.rust-lang.org/std/primitive.f64.html#method.is_nan (especially inverted : non_nan)

https://doc.rust-lang.org/std/primitive.f64.html#method.is_finite

https://doc.rust-lang.org/std/primitive.f64.html#method.is_normal

[Rolv-Apneseth]

@jprochazk do you think a new float(non_nan, finite, normal) rule would be the way to do this or should things like this just be implemented with a custom validator?