Setting `early_stopping_timeout` to `None` is not handled correctly

[VadimsAhmers]

While working with FEDOT, I discovered that the early_stopping_timeout parameter cannot be set to None. Attempting to do so results in the following errors:

>       lambda: self.generations.stagnation_time_duration >= max_stagnation_time,
        'Optimisation finished: Early stopping timeout criteria was satisfied'
    )
E   TypeError: '>=' not supported between instances of 'float' and 'datetime.timedelta'

../../golem/core/optimisers/populational_optimizer.py:75: TypeError

when timeout parameter is set and

>       lambda: self.generations.stagnation_time_duration >= max_stagnation_time,
        'Optimisation finished: Early stopping timeout criteria was satisfied'
    )
E   TypeError: '>=' not supported between instances of 'float' and 'NoneType'

../../golem/core/optimisers/populational_optimizer.py:75: TypeError

when both early_stopping_timeout and timeout parameters are None

Current Workaround:

Currently, to disable this parameter, one can use early_stopping_timeout=np.inf instead.

Expected Behavior:

Setting early_stopping_timeout=None should:

• Be accepted as a valid parameter value
• Effectively disable the early stopping timeout functionality