Function heapify

Fixes a heap violation starting at the given index. This function adjusts the heap rooted at index `i` to fix the heap property violation. It assumes that the subtrees rooted at left and right children of `i` are already heaps. # Arguments `arr` - A mutable reference to the array representing the heap. `i` - The index to start fixing the heap violation. `is_max_heap` - A boolean indicating whet

(arr: &mut [T], i: usize, is_max_heap: bool)