Initial version of xgboost on ray, featuring:
- Distributed training and predict support, tested on clusters of up to 600 nodes
- Fault tolerance: Restarting the whole run from latest checkpoint if a node fails
- Fault tolerance: Automatic scaling down/up when nodes die/become available again
- Data loading from various sources (CSV, Parquet, Modin dataframes, Ray MLDataset, pandas, numpy)
- Seamless integration with Ray Tune
- Initial Ray placement group support