Add a constructor for `IsogenyMap`. ```rust impl</* bounds */> IsogenyMap<'a, DOMAIN, CODOMAIN> { const fn new( x_numerator: &'a [BaseField<CODOMAIN>], x_denominator: &'a [BaseField<CODOMAIN>], ... ) → Self { Self { x_numerator, x_denominator, ... } } } ``` _Originally posted by @Pratyush in https://github.com/arkworks-rs/algebra/pull/517#discussion_r1035169648_