[REVIEW] RF: Add Poisson deviance impurity criterion

cpp/include/cuml/tree/algo_helper.h

@@ -22,6 +22,7 @@ enum CRITERION {
   ENTROPY,
   MSE,
   MAE,
+  POISSON,
   CRITERION_END,
 };
 

cpp/src/decisiontree/batched-levelalgo/builder.cuh

@@ -163,6 +163,22 @@ void grow_tree(const raft::handle_t& handle,
                                                              sparsetree,
                                                              num_leaves,
                                                              depth);
+  } else if (params.split_criterion == CRITERION::POISSON) {
+    grow_tree<PoissonObjectiveFunction<DataT, LabelT, IdxT>>(handle,
+                                                             data,
+                                                             treeid,
+                                                             seed,
+                                                             ncols,
+                                                             nrows,
+                                                             labels,
+                                                             quantiles,
+                                                             rowids,
+                                                             n_sampled_rows,
+                                                             unique_labels,
+                                                             params,
+                                                             sparsetree,
+                                                             num_leaves,
+                                                             depth);
   } else if (params.split_criterion == CRITERION::MSE) {
     grow_tree<MSEObjectiveFunction<DataT, LabelT, IdxT>>(handle,
                                                          data,