Add compareData() to AVL/binary tree structs.

data_structures/avl_tree/src/avl_tree.(c, h)
	-Add a `compareData()` function to `BinaryTree_Tree_t()`.

data_structures/binary_tree/src/binary_tree.(c, h)
	-Set `BinaryTree_Tree_t.compareData` in `AVLTree_create()`.