클래스 인식을 위한 __init__.py 추가

back-end2/src/controllers/__init__.py

back-end2/src/models/__init__.py

back-end2/src/models/builders/__init__.py

back-end2/src/services/__init__.py

back-end2/src/services/aggregated_services/__init__.py

back-end2/src/services/api/__init__.py

back-end2/src/utils/__init__.py

back-end2/src/utils/image/__init__.py