[FEATURE] Add a probe function for our transposition table

[DeveloperPaul123]

Search is going to get really complicated - would be nice to move the tt entry search code to the ttable itself and create a new probe function that returns a ProbeResult enum:

enum ProbeResult {
  CuttOff,
  Hit,
  Empty
};

fn probe(&self, depth: i16, key: u64) -> ProbeResult {
}