extract from camera

- add help description
- use f-strings
- handle plural correctly
- rename methods, use otp_url instead of line
- remove importlib.util
- move cv2 imports to top
- remove unnecessary global delcarations
- group image tests

requirements.txt

@@ -3,3 +3,4 @@ qrcode
 Pillow
 qreader
 opencv-python
+pyzbar