Refactor Validation class

[IroNEDR]

Currently the PyNomaly library is using a validation class that offers several methods that print a warning and return a bool. Based on the returned bool value we either call some other function or even call sys.exit(). The following things should be changed:

1. Rename methods: functions like _fit() should be renamed to indicate that it only checks something e.g. is_fit()
2. Consider whether a validation class is even necessary, since all except for one of it's methods are static
3. Throw proper, meaningful exceptions instead of calling sys.exit() if certain validation methods

[vc1492a]

1. Rename methods: functions like _fit() should be renamed to indicate that it only checks something e.g. is_fit()

Definitely.

2. Consider whether a validation class is even necessary, since all except for one of it's methods are static

The original intent of this class was to provide helpful warning messages and errors and ensure that proper data types and formats are expected prior to execution. If we believe we can do that with item 3 (below) and without the whole Validation class, then I am for it.

Throw proper, meaningful exceptions instead of calling sys.exit() if certain validation methods.

Yes, let's do it 🚀