Add Arbitrary in range to trait

[yancyribbens]

Looking for the ability to create an Arbitrary type from a range.

For example, Given a Type:

pub struct A(u64);

Then a type can be created from range with:

impl<'a> Arbitrary<'a> for A {
    fn arbitrary_in_range<T>(u: &mut Unstructured<'a>, range: ops::RangeInclusive<T>) -> Result<Self>
    where
        T: arbitrary::unstructured::Int,
    {
        let a = u.int_in_range(range)?.to_u64();
        Ok(A(a))
    }
}

Marking this as draft to request feedback about adding. Cheers.

[yancyribbens]

I just noticed #192 which overlaps with this PR.