Validator: implement eachElementOf(v).satisfies(predicate)

[JoelGunawan]

Example usage:

public:
    void Constraints() {
        CONS(eachElementOf(A).satisfies(TestSpec::isOdd));
    }

private:
    static bool isOdd(int val) {
        return val % 2 == 1;
    }

[JoelGunawan]

Currently eachElementOf(v).satisfies(predicate) only supports scalar types.