NERtcVideoCropMode constructor Null safety

1. netease_roomkit
2. netease_roomkit
3. NERtcVideoCropMode
4. NERtcVideoCropMode constructor

NERtcVideoCropMode class

1. Constructors
2. NERtcVideoCropMode
3. Properties
4. hashCode
5. runtimeType
6. Methods
7. noSuchMethod
8. toString
9. Operators
10. operator ==
11. Constants
12. crop_1x1
13. crop_4x3
14. crop_16x9
15. cropDefault