Examples for XGBoost Autologging

Two examples are provided to demonstrate XGBoost autologging functionalities. The xgboost_native folder contains an example that logs a Booster model trained by xgboost.train(). The xgboost_sklearn includes another example showing how autologging works for XGBoost scikit-learn models. In fact, there is no difference in turning on autologging for all XGBoost models. That is, mlflow.xgboost.autolog() works for all XGBoost models.