Add missing train parameter for sklearn interface. (#7629)
Add missing train parameter for sklearn interface. (#7629)

Some other parameters are still missing and rely on **kwargs, for instance parameters from
dart.
dmlc/xgboost,dmlc/xgboost,dmlc/xgboost,dmlc/xgboost,dmlc/xgboost,dmlc/xgboost