Added avl height benchmark

Lab2/bst/bst.cpp

@@ -58,3 +58,11 @@ void deleteTree(Tree *root) {
     delete root;
   }
 }
+
+int getHeight(Tree *root, int height) {
+  if (root == nullptr) return height;
+  height += 1;
+  int leftHeight = getHeight(root->left, height);
+  int rightHeight = getHeight(root->right, height);
+  return std::max(leftHeight, rightHeight) + 1;
+}