Refactor/feature layers id in fit

[paulnovello]

• Replace the name of the method assign_ood_labels_by_class with split_by_class since it is more appropriate.
• Put feature_layers_id argument in the method .fit. It seems more natural since .fit deals with the construction of the FeatureExtractor, and OODBaseDetector.__init__() with the parameters of the detector.
• Add a property requires_internal_features to OODBaseDetector to maintain the behavior where usage of detectors acting on internal features without specifying internal features would throw a ValueError. It was otherwise difficult because after PR score() returns information with predictions and labels #70 feature_layers_id is no longer used by methods that act on logits only so we cannot throw an error solely based on the criterion that feature_layers_id is None

[github-actions]

☂️ Python Coverage

current status: ✅

Overall Coverage

Lines	Covered	Coverage	Threshold	Status
1954	1786	91%	70%	🟢

New Files

No new covered files...

Modified Files

File	Coverage	Status
oodeel/init.py	100%	🟢
oodeel/datasets/ooddataset.py	91%	🟢
oodeel/methods/base.py	75%	🟢
oodeel/methods/dknn.py	100%	🟢
oodeel/methods/energy.py	100%	🟢
oodeel/methods/entropy.py	100%	🟢
oodeel/methods/mahalanobis.py	98%	🟢
oodeel/methods/mls.py	100%	🟢
oodeel/methods/odin.py	100%	🟢
oodeel/methods/vim.py	86%	🟢
TOTAL	95%	🟢

updated for commit: 06b5710 by action🐍

[cofri]

I don't know if you've already requested reviews, but this is my last contribution for the next 3 weeks 🏖️
Nice feature! It rocks 🚀

[y-prudent]

Good job! 💪