controller property Null safety

1. smooth_app
2. camera_helper
3. CameraHelper
4. controller property

CameraHelper class

1. Properties
2. hashCode
3. runtimeType
4. Methods
5. noSuchMethod
6. toString
7. Operators
8. operator ==
9. Static properties
10. controller
11. Static methods
12. findBestCamera
13. init
14. initController