Insert Interval
You are given an array of non-overlapping intervals intervals where intervals[i] = [start, end] sorted in ascending order by start. You are also given another interval newInterval = [start, end] that represents the start and end of another interval.
Insert newInterval into intervals such that intervals is still sorted in ascending order by start and intervals still does not have any overlapping intervals (merge overlapping intervals if necessary).
insertInterval([[1, 3], [6, 9]], [2, 5]);
// [[1, 5], [6, 9]]