refactor: logits as attributes of FeatureExtractor

[paulnovello]

• Refactor answering #73
• Also add missing tests to check the output of .score().

[github-actions[bot]]

☂️ Python Coverage

current status: ✅

Overall Coverage

Lines	Covered	Coverage	Threshold	Status
1942	1791	92%	70%	🟢

New Files

No new covered files...

Modified Files

File	Coverage	Status
oodeel/extractor/keras_feature_extractor.py	94%	🟢
oodeel/extractor/torch_feature_extractor.py	98%	🟢
oodeel/methods/base.py	86%	🟢
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	96%	🟢

updated for commit: 3ebfb6c by action🐍