Implements hyperband method for hyperparameter
tuning. Various termination criteria can be set and combined. The
class 'AutoTuner' provides a convenient way to perform nested
resampling in combination with 'mlr3'. The hyperband algorithm was
proposed by Lisha Li, Kevin Jamieson, Giulia DeSalvo, Afshin
Rostamizadeh and Ameet Talwalkar (2018)