refactor augmentation to class, update classes.json, fix small bugs

preprocess-train.py

@@ -1,6 +1,5 @@
-from preprocessing import preprocess_annotations
+from augmentation import Augmentator
 from train import train_dataset, convert2rknn
 
-preprocess_annotations()
-train_dataset('2024-10-01')
-convert2rknn()
+Augmentator().augment_annotations(from_scratch=True)
+train_dataset(from_scratch=True)