feat: Implement a classifier for rock, paper and scisssor gesture

[Juliaj]

Main Changes

• Data processing utilities: using MediaPipe framework to extract hand landmarks.
• Model implementation: Added HandGestureClassifier using scikit-learn (RandomForestClassifier) to classify rock-paper-scissors gestures from hand landmarks.
• Training and prediction scripts: Implemented train.py for end-to-end training and predict.py for inference on single image.

Testing

• Unit tests added.