Unit Tests for Unit8/Example01

Tests for AlgoDat.Tree<T>:

bool IsHeap(Node<T> node): Checks if key in parentnode of subtree is smaller than the keys in childnodes.

bool IsComplete(Node<T> node): Checks if the tree is properly filled.

bool CheckHeapProperties(Node<T>? node): Checks if IsHeap() and IsComplete() are true.