Function VectorIt

cpp/src/arrow/util/iterator_test.cc:119–121

Non-templated version of VectorIt to allow better type deduction

// Non-templated version of VectorIt<T> to allow better type deduction
inline Iterator<TestInt> VectorIt(std::vector<TestInt> v) {
  return MakeVectorIterator<TestInt>(std::move(v));
}

template <typename Fn, typename T>
inline Iterator<T> FilterIt(Iterator<T> it, Fn&& fn) {