Add ValueRangeDetector

[viktorbeck98]

Detects numerical values that lie outside the trained min-max-range as anomalies.

[ernstleierzopf]

also add files to
detectors/init.py
docs/detectors/detectorname.md
docs/detectors.md

[ernstleierzopf]

What is the correct way to handle non-numeric values, that appear during training of the ValueRangeDetector for configured / watched variables?

As I see it, there are two ways to handle this situation:

1. Print error message in logger like logger.error(f"Non-numeric value '{v}' appeared in training of {self.__class__.__name__} with the name {self.name}.") and exit to program. This option is quite drastic, but I would prefer it, because the user probably configured the wrong variable and wants to fix the error as soon as possible.
   This seems to be the behavior of the old ValueRangeDetector in logdata-anomaly-miner. However, there was no exception handling in that case, which I would like to include for controlled exiting of the service.
2. Just print an error message and remove the affected data. (current implementation)

[viktorbeck98]

I had a talk with @landauermax and we think it would probably be the best if option 2 would be the default. However, it would be nice to have an optional parameter that enables option 1 (smth like ignore_non_numerical_val=False).